Performance information

• Synthesis and high-field magnetic measurement of Ba2Sn2+xMe1+xFe10-2xO22
  H. Harasawa; H. Mitamura; M. Tokunaga; K. Kakizaki; K. Kamishima
  Journal of the Magnetics Society of Japan, Volume：48, Number：5, First page：88, Last page：93, Sep. 2024, [Reviewed], [Last, Corresponding]
  The Magnetics Society of Japan, Scientific journal
  DOI：https://doi.org/10.3379/msjmag.2409r002
  DOI ID：10.3379/msjmag.2409r002, ISSN：1882-2924, eISSN：1882-2932
• Stable Formation and Enhanced Magnetism: Modified Compositions in 18H-type Hexaferrite Crystals
  Kenji Kamishima; Masato Takayama; Taro Yasui; Kazuya Watanabe; Koichi Kakizaki
  Journal of the Physical Society of Japan, Volume：93, Number：8, First page：084802, Jul. 2024, [Reviewed], [Lead, Corresponding]
  Physical Society of Japan, Scientific journal
  DOI：https://doi.org/10.7566/jpsj.93.084802
  DOI ID：10.7566/jpsj.93.084802, ISSN：0031-9015, eISSN：1347-4073
• Synthesis of Fe2+-based 18H-type ferrite, Ba5Fe2+2-xFe3+12+2xTi3-xO31　　　　　　　　　　　　　　　
  Sora Nakahara; Koichi Kakizaki; Kenji Kamishima
  Journal of Magnetism and Magnetic Materials, Volume：602, First page：172175, Last page：172175, May 2024, [Reviewed], [Last, Corresponding]
  Elsevier BV, Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2024.172175
  DOI ID：10.1016/j.jmmm.2024.172175, ISSN：0304-8853
• Uncovering a New Crystal Structure: 18H-type Ferrite Compounds
  Kenji Kamishima
  Materia Japan, Volume：62, Number：9, First page：594, Last page：599, Sep. 2023, [Reviewed], [Invited], [Lead, Corresponding]
  Japan Institute of Metals, Scientific journal
  DOI：https://doi.org/10.2320/materia.62.594
  DOI ID：10.2320/materia.62.594, ISSN：1340-2625, eISSN：1884-5843
• Synthesis of (Ca, Sr)-based W-type hexagonal ferrite　　　　　　　　　　　　　　　
  Kenji Kamishima; Takehiro Sekigawa; Koichi Kakizaki; Kowashi Watanabe
  Journal of Magnetism and Magnetic Materials, Volume：574, May 2023, [Reviewed], [Lead, Corresponding]
  This investigation has examined the synthesis conditions and magnetic properties of (Ca, Sr)-based W-type hexagonal ferrite. Substituting Ca for Sr in CaxSr1−xZn2Fe16O27 (where 0≤x≤1) resulted in the formation of the W-type structure at x≤0.7 sintered at TS = 1250 and 1300°C. However, these W-type samples were accompanied by secondary spinel and hematite phases, making it necessary to modify the initial composition to form a single W-type phase. Eliminating the potential compositions of these secondary phases resulted in the optimal single-phase-forming condition of Ca: Sr: Zn: Fe = 0.55: 0.45: 0.88: 11.6 and TS = 1200°C. The magnetization of this sample at 5 K was 130.7 A m2/kg at 7 T, consistent with a model of a collinear magnetic structure. The Curie temperature of this sample was found to be 350°C.
  Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2023.170670
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85151786216&origin=inward
  DOI ID：10.1016/j.jmmm.2023.170670, ISSN：0304-8853, SCOPUS ID：85151786216
• Synthesis conditions of off-stoichiometric BaFe₉LiO₁₅ polycrystalline and single-crystal samples　　　　　　　　　　　　　　　
  K. Kamishima; H. Takahashi; K. Kakizaki; I. Yanase; T. Fujihara
  Journal of Crystal Growth, Volume：593, Sep. 2022, [Reviewed], [Lead, Corresponding]
  We have determined the phase diagrams of BaO-Li2O-Fe2O3 about BaFe9LiO15, which we initially came across with unfamiliar Bragg peaks through our attempts to synthesize a kind of Y-type hexaferrite, Ba2Me2Fe12O22 with Me2 = LiFe. The initial composition of Ba: Fe: Li = 2.5: 23: 2 allowed us to obtain the single phase of BaFe9LiO15 despite its off-stoichiometry. The conditions for the formation of the single phase of BaFe9LiO15 were confirmed by synthesizing about 40 initial composition samples around Ba: Fe: Li = 2.5: 23: 2 at 1000, 1050, and 1100°C, respectively. Single crystals of BaFe9LiO15 were separated from the internal part of a disk-shaped sample with the initial composition of Ba: Fe: Li = 2.5: 23: 2 sintered at 1200°C. X-ray crystallography for a single crystal showed that the oxide has an orthorhombic structure (space group: Cmca) with a = 11.527(8) Å,b = 10.253(7) Å, and c = 9.450(6) Å, which is consistent with the previously-reported Rietveld analysis result of synchrotron-radiation X-ray diffraction experiments on BaFe9LiO15 powder. The temperature dependence of magnetization at μ0H = 0.1 T showed a slight change in slope around 200°C, consistent with the previously-reported antiferromagnetic transition temperature determined by Mössbauer spectroscopy.
  Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2022.126755
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85132707032&origin=inward
  DOI ID：10.1016/j.jcrysgro.2022.126755, ISSN：0022-0248, SCOPUS ID：85132707032
• High Saturation Magnetization Calcium-Zinc Spinel Ferrite Prepared by Rapid Cooling　　　　　　　　　　　　　　　
  J. Hashimoto; K. Kakizaki; K. Kamishima
  Journal of the Magnetics Society of Japan, Volume：46, Number：3, First page：58, Last page：63, 2022, [Reviewed], [Last, Corresponding]
  To obtain a high magnetization Ca-Zn-based spinel ferrite, we investigated the synthesis conditions and magnetic properties of samples with compositions of Ca: Zn: Fe = 0.5: 2.5: 16-x (x = 1, 2, 3, 4, 5, 6, and 7) sintered at 1300°C and then cooled under different conditions (-200°C/hour or quenched in water). Quenching the sample at x = 3 resulted in the best sample with the highest magnetization of 146 emu/g at T = 1.8 K. We estimated the Fe2+ amount and molar ratio of the sample by using thermogravimetry/ differential thermal analysis (TG/DTA). The large lattice constant implied that the spinel contained Ca2+ ions at its transition metal sites, which possibly led to a cationic distribution contributing to the high magnetization.
  Scientific journal
  DOI：https://doi.org/10.3379/msjmag.2205R002
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85130270806&origin=inward
  DOI ID：10.3379/msjmag.2205R002, ISSN：0285-0192, eISSN：1882-2932, SCOPUS ID：85130270806
• Restoration of the collinear spin arrangement in non-magnetic-ion-substituted M-type hexaferrite by high magnetic fields　　　　　　　　　　　　　　　
  K. Kamishima; A. Yonezawa; K. Kakizaki; A. Miyake; H. Mitamura; M. Tokunaga
  Journal of Magnetism and Magnetic Materials, Volume：538, First page：168251, Last page：168251, Nov. 2021, [Reviewed], [Lead, Corresponding]
  Elsevier {BV}, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2021.168251
  DOI ID：10.1016/j.jmmm.2021.168251, ISSN：0304-8853, ORCID：98758008
• Discovery of the new crystallographic phase of an exotic magnetic oxide: 18H-type hexaferrite　　　　　　　　　　　　　　　
  Kazuya Watanabe; Takashi Fujihara; Kowashi Watanabe; Koichi Kakizaki; Kenji Kamishima
  Journal of the Physical Society of Japan, Volume：89, Number：1, 2020, [Reviewed], [Last, Corresponding]
  We have found an exotic magnetic oxide with unreported Bragg peaks through our attempts to substitute Zn2+ and Ti4+ for 2Fe3+ in Zn2Y-type hexaferrite (Ba2Zn2Fe12O22). Single crystals of the magnetic oxide were grown by a self-flux method with the approximate initial composition (Ba: Zn: Ti: Fe ¼ 2: 1: 1: 6) estimated by subtracting a zinc S-block composition (Zn2Fe4O8) from the Zn-Ti substituted Y-type composition of Ba2Zn3TiFe10O22. X-ray crystallography for a single crystal revealed that the magnetic oxide has a hexagonal structure (space group: P63= mmc) with a = 5.8383(3) Å and c = 43.1422(19) Å. This crystal structure can be interpreted as intercalation of three hexagonal BaTiO3 blocks into one T-block (Ba2Fe8O14) in the Y-type hexaferrite structure (T-S block stacking), which was conjectured under the name of “18H-type” hexaferrite. The actual composition of the crystal was estimated to be Ba5Fe12+2xTi3−xZn2−xO31 with x' 0:5. Polycrystalline samples of Ba5Fe12+2xTi3−xZn2−xO31 were successfully prepared at 0 ≤ x ≤ 1.0 and showed the Curie temperatures between 301 and 437 K. The assumption of a collinear ferrimagnetic structure in the 18H-type unit cell successfully explained the magnetization of Ba5Fe12+2xTi3−xZn2−xO31 at T = 5 K.
  Scientific journal
  DOI：https://doi.org/10.7566/JPSJ.89.014704
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85078593332&origin=inward
  DOI ID：10.7566/JPSJ.89.014704, ISSN：0031-9015, eISSN：1347-4073, SCOPUS ID：85078593332
• Synthesis and magnetic properties of M²⁺Ti⁴⁺ substituted Ba₁₂Fe₂₈Ti₁₅O₈₄　　　　　　　　　　　　　　　
  N. Yasuda; S. Kittaka; Y. Kono; T. Sakakibara; K. Kakizaki; K. Kamishima
  Journal of the Magnetics Society of Japan, Volume：44, Number：3, First page：70, Last page：74, 2020, [Reviewed], [Last, Corresponding]
  We investigated the synthesis conditions and magnetic properties of M-Ti substituted Ba12Fe28Ti15O84 with initial compositions of Ba12Fe28-2xTi15+xMxO84 (M = Zn, Mg, Ni, Cu, and Co) sintered at 1100-1300°C. The highest substitution amounts of M-Ti for Fe were consistent with the Ti-ion preference of each transition metal site reported before, suggesting that substituted Ti ions also preferred the sites with high Ti-ion occupancies. The spontaneous magnetizations and Curie temperatures were decreased as the substitution amount x was increased, which means that the substitution weakened the super-exchange interactions between Fe-O-Fe. The highest Zn-Ti substitution rate was lower than the other M-Ti substitution rates, which implies that Zn ions tend to enter specific M(2) and M(14) sites in Ba12Fe28Ti15O84. The sweep of the magnetic field from 0 to 80 kOe changed the relative dielectric constant of Ba12Fe28Ti15O84 by 0.283%. This variation of the dielectric constant caused by the application of magnetic fields is not negligible, showing that this compound should be categorized as a multiferroic material.
  Scientific journal
  DOI：https://doi.org/10.3379/msjmag.2005R004
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85084264273&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85084264273&origin=inward
  DOI ID：10.3379/msjmag.2005R004, ISSN：0285-0192, eISSN：1882-2932, SCOPUS ID：85084264273
• Flux growth and magnetic properties of single crystals of hexagonal ferrite structures and a long-range-order structure　　　　　　　　　　　　　　　
  T. Saho; T. Fujihara; K. Kakizaki; K. Kamishima
  Journal of the Magnetics Society of Japan, Volume：44, Number：4, First page：91, Last page：95, 2020, [Reviewed], [Last, Corresponding]
  We prepared single crystals of six typical hexaferrites (M-type, W-type, X-type, Y-type, Z-type, and U-type) in order to investigate their formation, crystal size, and magnetic properties. In addition, we also investigated the conditions of single-crystal formation at several flux concentrations and cooling rates. We found that the growth of single crystals on the MY-line (Y-and Z-type) became more significant than that on the MS-line (W-type) under a slow-cooling condition. In contrast, the single crystals on the MS-line appeared with a relatively high cooling rate of 10°C/h., where the single crystals did not grow large. By using the self-flux method, we succeeded in synthesizing single crystals with a more complex structure with a possibility of being M2Y7 on the MY-line and investigating the magnetic properties.
  Scientific journal
  DOI：https://doi.org/10.3379/msjmag.2007R001
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85087379597&origin=inward
  DOI ID：10.3379/msjmag.2007R001, ISSN：0285-0192, eISSN：1882-2932, SCOPUS ID：85087379597
• Preparation of Sr-based hexagonal ferrite by controlling the oxidation state of Fe　　　　　　　　　　　　　　　
  Meguro M.; Kakizaki K.; Kamishima K.
  Transactions of the Materials Research Society of Japan, Volume：43, Number：3, First page：183, Last page：186, Jun. 2018, [Reviewed], [Last, Corresponding]
  We have investigated synthesis conditions and magnetic properties of Sr₂Fe²⁺₂Fe³⁺₁₂O₂₂ (Sr₂Fe₂Y). The main Y-type phase was observed for the sample synthesized with the initial composition of Sr:Fe²⁺:Fe³⁺=1.5:2:8 sintered at T_S=1200℃ and P_O2=10 Pa. The Curie temperature of Sr₂Fe₂Y was 643 K. The magnetization was 45.0 Am²/kg at T= 5 K and μ₀H=7 T. The difference in magnetization from the ideal collinear spin arrangement of Sr₂Fe₂Y is due to the existence of a minor Fe₃O₄-like spinel phase. The yield of Sr₂Fe₂Y phase was estimated to be 83 wt.%, suggesting successful synthesis of the Sr₂Fe₂Y hexaferrite.
  The Materials Research Society of Japan, English
  DOI：https://doi.org/10.14723/tmrsj.43.183
  DOI：https://doi.org/10.7566/jpsj.89.014704_references_DOI_WCaCRVotoVcsUCduXW0H2kbgfQQ
  DOI ID：10.14723/tmrsj.43.183, ISSN：1382-3469, eISSN：2188-1650, CiNii Articles ID：130007382955
• Optimum Conditions for Synthesizing Fe Substituted Hibonite　　　　　　　　　　　　　　　
  Nagumo H.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：42, Number：1, First page：1, Last page：4, 2018, [Reviewed], [Last, Corresponding]
  We investigated the synthesis conditions and magnetic properties of Fe substituted hibonite with initial compositions of CaAl_xFe_y−xO_19−δ (1 ≤ x ≤ 3, 5 ≤ y ≤ 9) and CaAl_xFe_8-xO_19−δ (0.5 ≤ x ≤ 1.6) sintered at 1200–1300ºC. The optimum conditions for synthesizing the best magnetic hibonite were found to be the initial composition of Ca:Al:Fe = 1:0.6:7.4 and the sintering temperature of 1250ºC. The best magnetic hibonite was magnetized at 75.0 A·m²/kg at T = 5 K and μ₀H = 7 T. This magnetic moment can be interpreted with a model of the collinear magnetic structure. The Curie temperature of the best magnetic hibonite was 330ºC, which was the highest among those of iron-substituted hibonite samples.
  The Magnetics Society of Japan, English
  DOI：https://doi.org/10.3379/msjmag.1801r001
  DOI ID：10.3379/msjmag.1801r001, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130006301660, CiNii Books ID：AA12749208
• Crystal orientation and magnetic properties of PdSb added L10-FePt system thin films　　　　　　　　　　　　　　　
  Koichi Kakizaki; Satoshi Takakuwa; Kenji Kamishima
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：64, Number：7, First page：355, Last page：358, Jul. 2017, [Reviewed]
  FePt thin films with L10 ordered structure are candidates for high-density magnetic recording media because of their high uniaxial magnetic anisotropy energy. The (Fe0.395Pt0.395Cu0.15 P0.02Pd0.04)100-xSbx thin films with various x were deposited directly on quartz glass substrates by a sputtering method. FePt ordered alloy thin films with (001) preferential orientation were achieved in Sb content of x ≥ 8.0 at.% with post-Annealing at 600°C for 1 hour under reduced pressure in a H2 atmosphere. However, the coercivity of these thin films decreased dramatically due to growing of the crystal grains. Therefore, in this study, we prepared the PdSb-FePt-(C4F8)n granular thin films to improve the coercivity. The Fe0.44Pt0.44Pd0.04Sb0.08-(C4F8)n granular thin film deposited at C4F8 partial pressure of 0.1 mTorr then annealed at 700°C for 1 hour under reduced pressure in a H2 atmosphere exhibited a large coercivity of 30 kOe.
  Journal of the Japan Society of Powder and Powder Metallurgy, Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.64.355
  DOI ID：10.2497/jjspm.64.355, ISSN：0532-8799, SCOPUS ID：85026385592
• Synthesis and magnetic properties of Fe substituted hibonite　　　　　　　　　　　　　　　
  Nagumo H.; Watanabe K.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：41, Number：2, First page：20, Last page：24, 2017, [Reviewed], [Last, Corresponding]
  We have investigated the synthesis conditions and magnetic properties of Fe substituted hibonite with initial compositions of CaAl_12-xFe_xO₁₉ (0≤x≤12) and CaAl_10-xFe_xO_19-δ (0≤x≤10). The Fe doped hibonite can be synthesized at a sintering temperature of 1300˚C. The X-ray diffraction patterns of Fe substituted hibonite samples are in good agreement with the pattern of hibonite. The lattice parameter increased due to the difference between the radius of Al³⁺ and that of Fe³⁺. The magnetization and Curie temperature of the best sample (CaAl₂Fe₈O_19-δ) are 31 emu/g and 290˚C, respectively.
  The Magnetics Society of Japan, English
  DOI：https://doi.org/10.3379/msjmag.1701r001
  DOI ID：10.3379/msjmag.1701r001, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130005401748, CiNii Books ID：AA12749208
• Optimum preparation conditions of Fe-deficient Ca-based M-type ferrite　　　　　　　　　　　　　　　
  Shigemura M.; Watanabe K.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：41, Number：1, First page：10, Last page：13, 2017, [Reviewed], [Last, Corresponding]
  We investigated synthesis conditions and magnetic properties of Fe-deficient Ca-based hexagonal ferrites, Ca_1−xLa_xFe_yO_19−σ (x = 0.1–0.3, y = 2.0–10), and found the formation of M-type ferrite at x = 0.1–0.3 and y = 7.0–9.0 above 1200°C. Samples of y = 2.0–6.0 showed deviation from the initial compositions since molten calcium-rich oxide (possibly CaFe₂O₄) leaked out from the samples above 1200°C. The X-ray diffraction pattern of Ca_0.8La_0.2Fe_8.0O_19−σ sintered at 1250°C demonstrates the single phase of M-type hexagonal ferrite. The saturation magnetization of this sample was 68.0 Am²/kg at room temperature and its Curie temperature was about 400°C, which is slightly lower than that of the Sr-based M-type ferrite (460°C).
  The Magnetics Society of Japan, English
  DOI：https://doi.org/10.3379/msjmag.1611r002
  DOI ID：10.3379/msjmag.1611r002, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130005239721, CiNii Books ID：AA12749208
• Synthesis of non-magnetic-ion-substituted Ca-based M-type ferrite　　　　　　　　　　　　　　　
  Shigemura M.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：41, Number：5, First page：94, Last page：98, 2017, [Reviewed], [Last, Corresponding]
  We investigated the synthesis conditions and magnetic properties of non-magnetic-ion-substituted Ca-based hexagonal ferrites, Ca_0.8La_0.2Fe_8.0−2xMg_xTi_xO_19−σ (x = 0.1–3.5) and Ca_0.8La_0.2Fe_y−xAl_xO_19−σ (x = 1.0–5.0, y = 8.0–10). We found that Mg-Ti-substituted Ca-based M-type ferrites formed at x = 0.1 and 0.2 at above 1225ºC. The sample at x = 0.1 showed the crystallographic single phase of M-type ferrite. The minimum Curie temperature of the Mg-Ti-substituted samples was 367ºC. Also, we found that the Al-substituted Ca-based M-type ferrites had the main phase of M-type ferrite in all samples. As the amount of substituted Al increased, the saturation magnetization and the Curie temperature decreased, and the coercivity increased. As the amount of substituted Al increased by Δx = 1, the Curie temperature decreased by ΔT_C = 50–70ºC. Al-substituted samples of x = 1.0 and 2.0 sintered at 1300ºC had the single phase of M-type ferrite.
  The Magnetics Society of Japan, English
  DOI：https://doi.org/10.3379/msjmag.1708r001
  DOI ID：10.3379/msjmag.1708r001, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130006041674, CiNii Books ID：AA12749208
• Synthesis and Magnetic Properties of (Zn²⁺Ti⁴⁺) Substituted W-type and Y-type Ferrites　　　　　　　　　　　　　　　
  Watanabe K.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：41, Number：6, First page：127, Last page：131, 2017, [Reviewed], [Last, Corresponding]
  We report the synthesis of (Zn²⁺Ti⁴⁺) substituted hexagonal ferrites, BaZn₂(Zn_0.5Ti_0.5)_xFe_16-xO₂₇ (W-type) and Ba₂Zn₂(Zn_0.5Ti_0.5)_xFe_12-xO₂₂ (Y-type), and the relationship between their composition and magnetic properties. Substituted W-type ferrite was synthesized in the region of 0.0 ≤ x ≤ 1.5. A decrease in the Curie temperature of the W-type phase indicated that the exchange interactions between the Fe³⁺ ions weakened due to the substitution of Zn²⁺ and Ti⁴⁺ ions. Spontaneous magnetization (σ_S) at x = 0.5 was similar to that at x = 0.0. This reflects the equal distribution of nonmagnetic Zn²⁺ and Ti⁴⁺ ions to spin down sites and spin up sites, respectively. At x > 0.5, σ_S decreased clearly, which was possibly caused by a deviation from the collinear arrangement. Substituted Y-type ferrite was also obtained up to x = 0.5. The Y-type phase is more unstable than the W-type phase with respect to this substitution rate.
  The Magnetics Society of Japan, English
  DOI：https://doi.org/10.3379/msjmag.1710r001
  DOI ID：10.3379/msjmag.1710r001, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130006192326, CiNii Books ID：AA12749208
• Synthesis and magnetic characterization of Sr-based Ni₂X-type hexaferrite　　　　　　　　　　　　　　　
  K. Kamishima; T. Mashiko; K. Kakizaki; M. Sakai; K. Watanabe; H. Abe
  AIP Advances, Volume：5, Number：10, First page：107132 1-10, Oct. 2015, [Reviewed], [Lead, Corresponding]
  We have investigated the synthesis conditions, and the magnetic properties of the Sr2Ni2X-type hexagonal ferrite, Sr2Ni2Fe28O46. The Sr2Ni2X-type hexaferrite was synthesized at 1240 degrees C. The spontaneous magnetization at 5 K was 44.2 mu(B)/f.u., suggesting that most of the Ni2+ ions are at the up-spin octahedral sites in the spinel-structure blocks within the model of a Neel-type collinear ferrimagnetic structure. The Curie temperature of the Sr2Ni2X-type hexaferrite was estimated to be T-C[Sr2Ni2X] = 472 degrees C. This is consistent with the difference of the block stacking structures of SrM-type, Sr2Ni2X-type, SrNi2W-type, and nickel spinel ferrites. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4934792
  DOI ID：10.1063/1.4934792, ISSN：2158-3226, Web of Science ID：WOS:000364228800032
• Crystallographic and magnetic properties of Cu₂U-type hexaferrite　　　　　　　　　　　　　　　
  K. Kamishima; R. Tajima; K. Watanabe; K. Kakizaki; A. Fujimori; M. Sakai; K. Watanabe; H. Abe
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：375, First page：54, Last page：60, Feb. 2015, [Reviewed], [Lead, Corresponding]
  We have investigated the synthesis conditions, and the magnetic properties of the Cu2U-type hexagonal ferrite, Ba4Cu2Fe36O60. The Cu2U-rype hexaferrite was synthesized at the sintering temperature of 1050 degrees C with the initial composition of Ba4.4Cu2Fe37.6O62.8 (Cu2U + 0.2T-block). The saturation magnetizations at 300 K and 5 K are 46.8 A m(2)/kg and 65.0 A m(2)/kg, respectively. The Curie temperature is 420 degrees C which is lower than that of the M-type ferrite (450 degrees C) but higher than that of the Cu2Y-type ferrite (320 degrees C). The amount of the nonmagnetic impurity in this sample is estimated to be about 10 wt% by the electron probe micro analysis. We estimated the expected saturation magnetization to be 652 A m(2)/kg, by assuming the model of a Neel-type ferrimagnetic structure and the reduction of magnetization by the 10 wt% nonmagnetic impurity. This is consistent with the observed magnetization of 65.0 A m(2)/kg at 5 K. (C) 2014 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2014.09.055
  DOI ID：10.1016/j.jmmm.2014.09.055, ISSN：0304-8853, eISSN：1873-4766, Web of Science ID：WOS:000344949800009
• Synthesis and magnetic properties of Fe₂W and Fe₂Y hexaferrites　　　　　　　　　　　　　　　
  Koide M.; Kakizaki K.; Kamishima K.
  Journal of the Magnetics Society of Japan, Volume：39, Number：4, First page：147, Last page：150, 2015, [Reviewed], [Last, Corresponding]
  We have investigated the synthesis conditions, and the magnetic properties of BaFe²⁺₂Fe³⁺₁₆O₂₇ (Fe₂W) and Ba₂Fe²⁺₂Fe³⁺₁₂O₂₂ (Fe₂Y). It is found that Fe₂W can be synthesized at a sintering temperature of 1300°C and Fe₂Y can be synthesized at a sintering temperature of 1000°C. The X-ray diffraction patterns for Fe₂W and Fe₂Y samples are in good agreement with the pattern of BaCo²⁺₂Fe³⁺₁₆O₂₇ (Co₂W) and that of Ba₂Co²⁺₂Fe³⁺₁₂O₂₂ (Co₂Y). It is also found that the Curie temperatures of Fe₂W and Fe₂Y ferrites are 503 and 375°C, respectively.
  The Magnetics Society of Japan, Japanese
  DOI：https://doi.org/10.3379/msjmag.1506r003
  DOI：https://doi.org/10.7566/jpsj.89.014704_references_DOI_BYFenyYFdPfKYNSahsBwYyjr44E
  DOI ID：10.3379/msjmag.1506r003, ISSN：1882-2924, eISSN：1882-2932, CiNii Articles ID：130005087628, CiNii Books ID：AA12297999
• Small ordered magnetic moment in a weak itinerant electron ferromagnet Sc₃In　　　　　　　　　　　　　　　
  K. Kamishima; R. Note; T. Imakubo; K. Watanabe; H. A. Katori; A. Fujimori; M. Sakai; K. V. Kamenev
  JOURNAL OF ALLOYS AND COMPOUNDS, Volume：589, First page：37, Last page：41, Mar. 2014, [Reviewed], [Lead, Corresponding]
  We performed neutron diffraction study of Sc-In alloy which indicates that the ordered magnetic moment in this material is intrinsically tiny. This tiny magnetic moment (0.04-0.05 mu(B)/Sc) is not caused by the uncompensated antiferromagnetic ordering of large magnetic moments. The temperature dependence of the resistivity is in proportion to T-3/2, which suggests that this material is naturally close to the quantum critical point where ferromagnetism vanishes. This is consistent with the fact that this material shows ferromagnetism in an extremely narrow range of compositions which is typical of materials exhibiting quantum critical phenomenon. In the vicinity of the Curie temperature the magnetization depends on magnetic fields as M-5 proportional to mu H-0. This behavior for itinerant ferromagnets can be explained by assuming that the total spin fluctuation amplitude is conserved. (C) 2013 Elsevier B. V. All rights reserved.
  ELSEVIER SCIENCE SA, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jallcom.2013.11.032
  DOI ID：10.1016/j.jallcom.2013.11.032, ISSN：0925-8388, eISSN：1873-4669, Web of Science ID：WOS:000330181400006
• Magnetic properties of La-Co substituted Ba ferrite thin films prepared by a sol-gel method　　　　　　　　　　　　　　　
  H. Yoshiga; K. Kamishima; N. Hiratsuka; K. Kakizaki
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：61, First page：S314, Last page：S317, 2014, [Reviewed]
  La-Co substituted BaM (La-CoBaM) thin films have been prepared by a sol-gel technique involving a spin coating of metal-organic compounds. We report the effects of Pt under-layer on the c-axis orientation of La-CoBaM films and their magnetic properties. On the Pt under-layer with the thickness of 120 nm whose '111' axis oriented perpendicular to substrate surface, the La-CoBaM films with the thickness ranging from 20 to 95 nm were coated at room temperature. These coated films were annealed at 900�C for 5h. in air. The Hc⊥/Hc// value for the La-CoBaM films with the thickness of 20 nm was 3.9 that was the largest of all samples. The c-axis of magnetoplumbite phase was oriented perpendicular to the film surface, that was caused by the effect of the (111) oriented Pt under-layer.
  Journal of the Japan Society of Powder and Powder Metallurgy, English, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.61.S314
  DOI ID：10.2497/jjspm.61.S314, ISSN：0532-8799, SCOPUS ID：84988026269
• Fine structure and magnetic properties of Ni-Zn ferrite nanoparticles prepared by ultrasonic spray pyrolysis　　　　　　　　　　　　　　　
  Nobuyuki Hiratsuka; Shozo Yuki; Kenji Kamishima; Koichi Kakizaki
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：60, Number：6, First page：257, Last page：262, Jun. 2013, [Reviewed]
  Crystalline nano-sized Ni1-xZnxFe2O 4 (x = 0 ∼ 1.0) particles were prepared by ultrasonic spray pyrolysis from the spray sol-gel solution with Ni-, Zn- and Fe-nitrates and citric acid. The crystal lattice constant increased lineally with increasing Zn ion contents according to the Vegard's rule. All the prepared particles had the size of less than 100 nm, which were calculated with Scherrer equation and were observed by TEM. The average particle size of the samples containing Zn ions was about 50 nm. The sample with x = 0.3 had the maximum magnetization of 63 emu/g, which was 80 percent of the bulk material. It was supposed that the sample contained a super paramagnetic substance. The coercivity of the samples was much larger than that of the bulk ferrites. The coercivity of the samples decreased with the increase of Zn ion contents. Curie temperature also decreased with the increase of Zn ion contents. However, these values were higher than those of the bulk materials because of existence of Fe2+ ions and heterogeneous octahedral site distribution of Zn ions.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.60.257
  DOI ID：10.2497/jjspm.60.257, ISSN：0532-8799, SCOPUS ID：84880539807
• Synthesis of a new U-type hexaferrite Ba₄Cu₂Fe₃₆O₆₀.　　　　　　　　　　　　　　　
  R. Tajima; K. Kamishima; K. Kakizaki; N. Hiratsuka; A. Fujimori; M. Sakai; K. Watanabe
  Trans. Mat. Res. Soc. Jpn, Volume：38, Number：3, First page：451, Last page：454, 2013, [Reviewed]
  English, Scientific journal
  DOI：https://doi.org/10.14723/tmrsj.38.451
  DOI ID：10.14723/tmrsj.38.451
• Preparation of nano Mn-Zn ferrite powders by ultrasonic spray pyrolysis method and their magnetic properties　　　　　　　　　　　　　　　
  Sho Tominaga; Kenji Kamishima; Koichi Kakizaki; Yoshihiro Ishimaru; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：59, Number：6, First page：337, Last page：341, Jun. 2012, [Reviewed]
  Nano-crystalline Mn-Zn ferrite powders (Mn1-xZn xFe2O4, x = 0∼1.0) have been prepared by ultrasonic spray pyrolysis method. Mn-Zn ferrite samples sintered at 700 °C had the single phase of spinel-type for all of the compositions. The lattice constant decreased with increasing Zn content and followed Vegard,s law. Curie temperature linearly decreased from that of MnFe2O4 (x = 0) with increasing Zn substitution rate. These results indicate that the Mn-Zn ferrite formed solid solution. The Mn-Zn ferrite particles were found to be in nano-size of 20∼30 nm by scanning electron microscopy. And their crystalline diameters were 15∼30 nm,determined by the use of Scherrer equation for X-ray diffraction peak broadening. Mn0.6Zn0.4Fe 2O4 sample had a magnetization value of 48 emu/g,which was lower than that of bulk sample (80emu/g). This is possibly caused by the existence of a disordered surface region on the nanoparticles, where the crystallographic and magnetic structures are disordered due to the nearly random distribution of cations and the canted spin arrangement.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.59.337
  DOI ID：10.2497/jjspm.59.337, ISSN：0532-8799, SCOPUS ID：84880444186
• Establishment of preparation process of hexagonal U-type ferrites Ba₄Me₂Fe₃₆O₆₀ (Me = Co, Ni, Mg) and their magnetic properties　　　　　　　　　　　　　　　
  Ryo Sasaki; Kenji Kamishima; Koichi Kakizaki; Yoshihiro Ishimaru; Masamichi Sakai; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：59, Number：3, First page：131, Last page：136, Mar. 2012, [Reviewed]
  We have established the preparation process of hexagonal U-type ferrites Ba4Me2Fe36O60 (Me = Co, Ni, Mg) and investigated their crystal structure and magnetic properties. The U-type ferrite single phase was not fabricated by using a conventional ceramic synthesis process which comprises two-steps: calcination and sintering. We have found that the U-type ferrites single phase can be obtained by a one-step sintering method that skips the calcination process. The single phase of the U-type ferrite was formed at a very narrow temperature at about 1250 °C. The values of saturation magnetization and the Curie temperature of Co2U ferrite were higher than those of Co2Z ferrite. Initial permeability of Co2U ferrite has a higher value than those of Ni2U and Mg2U ferrites. The U-type ferrite has a great potential for high frequency magnetic materials.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.59.131
  DOI ID：10.2497/jjspm.59.131, ISSN：0532-8799, SCOPUS ID：84880563658
• Magnetic property of pyrolytic carbon prepared on diamond powder in applied magnetic field　　　　　　　　　　　　　　　
  K. Kamishima; T. Tokue; D. Miyata; Y. Sato; F. Kadonome; T. Noda; K. Kakizaki; N. Hiratsuka; Y. Imanaka; T. Takamasu
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：324, Number：6, First page：1106, Last page：1111, Mar. 2012, [Reviewed], [Lead, Corresponding]
  We have prepared pyrolytic carbon samples from triethylamine on diamond powder in applied magnetic field of 6 T and investigated their magnetic properties. A ferromagnetic sample was obtained from the pyrolysis products even at room temperature, with spontaneous magnetization of 6.4 A m(2)/kg at 300 K, which is twice as large as that of the sample prepared without diamond powder. Therefore, the diamond powder seems to promote the formation of a three-dimensional ferromagnetic structure in pyrolytic carbon. (C) 2011 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2011.10.042
  DOI ID：10.1016/j.jmmm.2011.10.042, ISSN：0304-8853, Web of Science ID：WOS:000298864100035
• Formation of Flat, and Homogeneous Surfaces of Organized Molecular Films of Three-armed Polymerizable Amphiphiles with Metal-Scavenging Properties.　　　　　　　　　　　　　　　
  A. Fujimori; M. Taguchi; S. Hakozaki; K. Kamishima; B. Ochiai
  Langmuir, Volume：28, First page：10830, Last page：10837, 2012, [Reviewed]
  English, Scientific journal
  DOI：https://doi.org/10.1021/la301126y
  DOI ID：10.1021/la301126y
• Elucidation of formation process of NiFe₂O₄ ferrite nano-crystalline powder synthesized by sol-gel auto-combustion method　　　　　　　　　　　　　　　
  Nobuyuki Hiratsuka; Kyohei Kono; Kenji Kamishima; Koichi Kakizaki; Yoshihiro Ishimaru; Masamichi Sakai
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：58, Number：6, First page：334, Last page：341, Jun. 2011, [Reviewed]
  Nano-crystalline NiFe2O4 (NF) powder was prepared by a sol-gel auto-combustion method. Its crystal structure, morphology, particle size and magnetic properties were investigated and the formation process of nano-crystalline NF was elucidated. The as-dried Ni-Fe precursor (Ni/Fe=0.5) was calcined in air at 200-800°C for 4 hours. γ-Fe2O 3 powder was formed at about 210°C by the self-combustion of the gel, and was maintained at 200-400°C. Singlephase NF sample was obtained by being calcined at 600-800 °C. The NF particles were of nano-crystalline with crystallite diameters of 68.2-94.3 nm which were determined by the use of Scherrer equation for XRD peak broadening and the observation of TEM images. The sample calcined at 200 °C had a magnetization value of 44emu/g, which was lower than that of bulk γ-Fe2O3 (70 emu/g) because of a lot of vacancies at octahedral sites. Magnetization was increased gradually with increasing calcination temperature, and reached to the maximum value of 46 emu/g for the samples calcined at 700 and 800°C, which was in agreement with the magnetization of the bulk NF sample. Coercivity was decreased with increasing calcination temperature.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.58.334
  DOI ID：10.2497/jjspm.58.334, ISSN：0532-8799, SCOPUS ID：80052733699
• Crystal structure and magnetic properties of the carbon-based ferromagnet prepared by pyrolytic method under high magnetic field　　　　　　　　　　　　　　　
  Takashi Tokue; Kenji Kamishima; Daisuke Miyata; Yuki Sato; Koichi Kakizaki; Nobuyuki Hiratuka; Yasutaka Imanaka; Tadashi Takamasu
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：58, Number：3, First page：176, Last page：180, Mar. 2011, [Reviewed]
  We have prepared the carbon-based ferromagnets by pyrolytic method under high magnetic field and investigated their crystal structure and magnetic properties. The crystal structure was measured by the synchrotron X-ray diffraction experiment. The diffraction peak of a diamond was observed for the ferromagnetic samples. Thus, the carbon-based ferromagnet can be attributed to the ferromagnetic ordering of radical spins generated by defects in the diamond structure. And, the diffraction peak of a diamond of the ferromagnetic samples increased with the applied magnetic field in sample preparation. Therefore, the magnetic field may help to form a three dimensional ferromagnetic structure in the carbon-based ferromagnet. The highest magnetization was 3.0 emu/g at 300 K for the sample prepared under magnetic field at 6 T.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.58.176
  DOI ID：10.2497/jjspm.58.176, ISSN：0532-8799, SCOPUS ID：79958732198
• Crystallographic and magnetic properties of Cu₂X, Co₂X, and Ni₂X hexaferrites　　　　　　　　　　　　　　　
  Kenji Kamishima; Nobuyuki Hosaka; Koichi Kakizaki; Nobuyuki Hiratsuka
  JOURNAL OF APPLIED PHYSICS, Volume：109, Number：1, First page：013904 1-5, Jan. 2011, [Reviewed], [Lead, Corresponding]
  We have investigated the synthesis conditions and the magnetic properties of X-type hexagonal ferrites. It is found that Ba2Cu2Fe28O46 (Cu2X), Ba2Co2Fe28O46 (Co2X), and Ba2Ni2Fe28O46 (Ni2X) ferrites can be synthesized at a sintering temperature of 1250 degrees C. The x-ray diffraction patterns for Cu2X, Co2X, and Ni2X samples are in good agreement with the pattern calculated from the atomic coordinates for Ba2Fe30O46 (Fe2X), where two diffraction peaks at Q=2.24 and 2.30 angstrom(-1) are clearly observed in contrast with other M-, W-, Y-, and Z-types hexagonal ferrites. It is also found that the low-temperature spontaneous magnetizations of Cu2X, Co2X, and Ni2X ferrites are 47.5 mu(B)/f.u., 43.4 mu(B)/f.u., and 43.2 mu(B)/f.u., respectively. The cation distributions for Cu2X, Co2X, and Ni2X are discussed within the model of a Neel-type collinear ferrimagnetic structure. (C) 2011 American Institute of Physics. [doi:10.1063/1.3527933]
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.3527933
  DOI ID：10.1063/1.3527933, ISSN：0021-8979, Web of Science ID：WOS:000286219300078
• Preparation and magnetic properties of X-type hexaferrites with transition metal elements　　　　　　　　　　　　　　　
  Nobuyuki Hosaka; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：57, Number：12, First page：809, Last page：813, Dec. 2010, [Reviewed]
  The conventional synthesis of ferrite compounds consists of two-steps sintering processes. The first process is calcination to produce precursor of a desired ceramic object, and the second is to obtain the desired object. However, it was difficult to prepare X-type hexaferrite (Ba2Me 2+2Fe28O46· Me2X, Me = Co, Ni, Cu, Zn) samples by this method. Two-steps sintering of these samples resulted in formation of spinel, M and W-type ferrite phases. We have found that Me2X can be obtained by a one-step sintering method that skipped the calcination process. When this method is applied, the temperature range of Me2X formation was very narrow and about 1250°C. We measured the saturation magnetization at 2 K and room temperature, and examined the Curie temperatures Of Me2X samples produced by this method. These magnetic properties for Me2X samples relatively resemble those of MeFe 2O4 spinel ferrites, which suggests that Me2+ cations are distributed in spinel blocks in the Me2X crystal structure.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.57.809
  DOI ID：10.2497/jjspm.57.809, ISSN：0532-8799, SCOPUS ID：79953296296
• Magnetoelectric effect in multiferroic CoFe2O4-BaTiO3 composites　　　　　　　　　　　　　　　
  Haruka Tada; Kenji Kamishima; Koichi Kakizaki; Masamichi Sakai; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：57, Number：11, First page：716, Last page：721, Nov. 2010, [Reviewed]
  Co1-xFe2+xO4-2BaTiO3 (x = 0,0.1 and 0.2) samples were prepared by using a conventional ceramic method. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements were done on these samples and we confirmed that cobalt ferrite and BaTiO3 components were clearly separated in the composites. The samples exhibited both ferroelectric and ferromagnetic properties. This indicates the samples were multiferroic materials. The resistivity was increased with x, whereas the tetragonality of BaTiO3 was decreased with x. While a sample with x = 0.1 had the highest permittivity of 522, samples with x = 0 and 0.2 had lower permittivity, which may have been caused by leakage current and deterioration of the ferroelectricity of BaTiO3, respectively. This same sample with x = 0.1 also exhibited the highest ME coefficient of 0.2 mV/cm Oe. We expect that improved permittivity will lead to a higher ME coefficient.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.57.716
  DOI ID：10.2497/jjspm.57.716, ISSN：0532-8799, SCOPUS ID：79951526177
• Thermoelectric property of Sr and Cu substituted Ca₃Co₄O_9+δ　　　　　　　　　　　　　　　
  Naoya Kamigaito; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：57, Number：4, First page：237, Last page：241, Apr. 2010, [Reviewed]
  Ca3-xSrxCuyO9+δ (x = 0, 0.1, 0.3
  y = 0, 0.05, 0.1 ) samples were prepared by using a conventional ceramic method. The crystal structure, bulk density and thermoelectric properties of the samples were investigated. In the X-ray diffraction patterns of the samples sintered at 1100°C, the single phase of Ca3Co 4O9+δ was obtained. Lattice constants were increased with x and y, which suggested that Sr and Cu were substituted for Ca and Co in the Ca3Co4O9+δ structure, respectively. The sample with x = 0.3 and y = 0.1 got the highest density because the grain size bacame small and the void was removed. The highest density sample had the highest conductivity in all samples. The Seebeck coefficient didn't change by substitution. As a result, the sample with x=0.3 and y = 0.1 had the highest power factor in all samples because of increase of the conductivity by substitution.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.57.237
  DOI ID：10.2497/jjspm.57.237, ISSN：0532-8799, SCOPUS ID：77954717675
• Preparation of pyrolytic magnetic carbon under magnetic field　　　　　　　　　　　　　　　
  Kenji Kamishima; Daisuke Miyata; Yki Sato; Takashi Tokue; Koichi Kakizaki; Nobuyuki Hiratsuka; Yasutaka Imanaka; Tadashi Takamasu
  Journal of Physics: Conference Series, Volume：200, Number：SECTION 11, 2010, [Reviewed], [Lead, Corresponding]
  We have prepared pyrolytic carbon samples from triethylamine and investigated their magnetic properties. A ferromagnetic sample was obtained from the pyrolysis products even at room temperature, with spontaneous magnetization of 5 × 10-1 emu/g at 300 K. The magnetization was decreased with increasing temperature up to 500 K, but increased above 550 K. After this measurement, it was found that the magnetization at 300 K was changed to 6 × 10-1 emu/g. Another ferromagnetic sample has been also prepared by pyrolysis under high magnetic field of 2 Tesla. The spontaneous magnetization of this field-pyrolysis sample is 1.3 emu/g, which is twice as large as that of the above-mentioned sample prepared without magnetic field. Therefore, the magnetic field may help to form a ferromagnetic structure in pyrolytic carbon. © 2010 IOP Publishing Ltd.
  International conference proceedings
  DOI：https://doi.org/10.1088/1742-6596/200/11/112003
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77957069803&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77957069803&origin=inward
  DOI ID：10.1088/1742-6596/200/11/112003, ISSN：1742-6588, eISSN：1742-6596, SCOPUS ID：77957069803
• Crystal structure and magnetic properties of X-type hexagonal ferrite Ba2Ni2Fe28O46　　　　　　　　　　　　　　　
  Nobuyuki Hosaka; Yoshihisa Yamamoto; Seiji Kano; Jingsha He; Hiroshi Inada; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：57, Number：1, First page：41, Last page：45, Jan. 2010, [Reviewed]
  Ba2Ni2Fe28O46 (Ni2X) samples were prepared by using a conventional ceramic method. The crystal structure and magnetic properties of the samples were investigated. The X-ray diffraction patterns of the samples sintered at 1250 °C and 1300 °C were in agreement with the diffraction pattern simulated from the real space coordinates of Ba, Fe and O ions. The Curie temperature was found to be 478 °C, which was different from the Curie temperatures of M-type and Ni 2W-type hexaferrites. The single phase of X-type hexaferrite was obtained at 1250 °C, which suggests that the sintering processes should be carefully controlled for the synthesis of the X-type hexaferrite. The saturation magnetization of Ni2X-type hexaferrite was higher than that of M-type and W-type hexaferrite at room temperature. Whereas, the coercivity was lower than that of M-type hexaferrite.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.57.41
  DOI ID：10.2497/jjspm.57.41, ISSN：0532-8799, SCOPUS ID：77950506553
• High frequency characteristic of elements substituted hexagonal ferrites　　　　　　　　　　　　　　　
  Nobuyuki Hiratsuka; Koichi Kakizaki; Kenji Kamishima
  ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII, Volume：421-422, First page：541, Last page：545, 2010, [Reviewed]
  The initial permeability mu ' (at 0.1 GHz) of Ba(3)Co(2)R(0.1)Fe(23.9)O(41) (x=0.1, R=Gd, Dy, Ho, Yb) samples is higher than that of the Co(2)Z ferrite without substitution. In particular, mu ' of Gd(3+) substituted Z-type ferrite sample (x=0.1) is the highest of all samples. The substituted sample of Ba(3)Co(2)Ti(x)Zn(x)Fe(24-2x)O(41) with x=0.85 has a maximum mu ' of 24, which is twice as large as that of the non-substituted sample with x=0. Ba(3)Co(2-2x) Li(x)Fe(24+x)O(41)(x=0-1.0) are also prepared. The sample with x=0 shows mu ' of 8 at 50MHz. The maximum mu ' is 24.5 at x=0.3. An apparent magnetic anisotropy constant K*, calculated by using H(A)* and M(S), decreases. Therefore, the decrease of the magnetic anisotropy contributes to the increase of mu '.
  TRANS TECH PUBLICATIONS LTD, English, International conference proceedings
  ISSN：1013-9826, Web of Science ID：WOS:000279342100126
• Magnetic and Electronic Properties of BaTiO₃-(Ni,Cu,Zn)Fe₂O₄ Ceramic Composite: Reflection of Kepler Conjecture　　　　　　　　　　　　　　　
  Kenji Kamishima; Yoshitaka Nagashima; Koichi Kakizaki; Nobuyuki Hiratsuka; Kowashi Watanabe; Hiroshi Naganuma
  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：78, Number：12, First page：124801 1-5, Dec. 2009, [Reviewed], [Lead, Corresponding]
  Ceramic composites [xNi(0.15)Cu(0.3)nZn(0.55)Fe(2)O(4)-(1-x)BaTiO3] were successfully prepared by a direct solid-state reaction of raw materials (BaCO3, CuO, alpha-Fe2O3, NiO, TiO2, and ZnO). The composites are so homogeneous that the ferrite and BaTiO3 grains do not react with each other. The x-dependent permeability and permittivity are found to obey Maxwell-Garnett effective medium theory, which suggests that the composites consist of ferrite particles with barium titanate medium. This model, however, starts to deviate from the experimental data at x = 0.75, and the roles of medium and inclusions seem to be exchanged. It can be qualitatively explained by the fact that geometrical close-packing of spheres is limited up to about 74 vol% (Kepler conjecture).
  PHYSICAL SOC JAPAN, English, Scientific journal
  DOI：https://doi.org/10.1143/JPSJ.78.124801
  DOI ID：10.1143/JPSJ.78.124801, ISSN：0031-9015, Web of Science ID：WOS:000272985600045
• Preparation of pyrolytc magnetic carbon under magnetic field　　　　　　　　　　　　　　　
  Kenji Kamishima; Daisuke Miyata; Yuki Sato; Takashi Tokue; Koichi Kakizaki; Nobuyuki Hiratsuka; Yasutaka Imanaka; Tadashi Takamasu
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：56, Number：7, First page：456, Last page：460, Jul. 2009, [Reviewed], [Lead, Corresponding]
  We have prepared pyrolytic carbon samples from triethylamine and investigated their yields and magnetic properties. Ferromagnetic samples were obtained from the pyrolysis products even at room temperature. The yield of the ferromagnetic sample was increased by setting a magnetic circuit on the pyrolysis chamber. The magnetic field seemed to affect the triethylamine vapor and then increased the yield and the magnetization. Also, the synchrotron X-ray diffraction experiments were performed for these pyrolytic carbon samples. Diffraction peaks of iron or iron oxides were not observed for the ferromagnetic samples, whereas the major diffraction peaks of the intermediate graphite-diamond (IGD) structure were observed for the ferromagnetic samples. The best magnetization sample also showed the diffraction peaks of the diamond-like-carbon structure. Therefore, the magnetic field may help to form a three-dimentional ferromagnetic structure in pyrolytic carbon.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.56.456
  DOI ID：10.2497/jjspm.56.456, ISSN：0532-8799, SCOPUS ID：70350074613
• High-frequency and Magnetic Properties of Mn-Ti Substituted Co_2Z Ferrite　　　　　　　　　　　　　　　
  EGAWA W.; KAMISHIMA K.; KAKIZAKI K.; HIRATSUKA N.
  Transactions of the Magnetics Society of Japan, Volume：33, Number：3, First page：222, Last page：226, May 2009, [Reviewed]
  Ba₃Co₂Mn_0.5xTi_0.5xFe_24-xO₄₁ (x=0-0.6) samples were prepared by using a conventional ceramic method. The samples had a the single crystallographic phase of hexagonal Z-type ferrite, which suggests that Fe³⁺ ions are replaced by Mn²⁺ and Ti⁴⁺ ions. Substituted samples of Ba₃Co₂Mn_0.5xTi_0.5xFe_24-xO₄₁ with x=0.4 had a maximum μ' of 25.7 and a μ'×f_r of 17.6 GHz. The M-T curves exhibited an anomalous drop below the Curie temperature, which reflects the change from in-plane magnetic anisotropy to uniaxial anisotropy with increasing temperature. The temperature of the anomalous drop rose from 533 K to 559 K due to the substitution. This resulted in an improvement of μ' and μ'×f_r.
  The Magnetics Society of Japan, Japanese
  DOI：https://doi.org/10.3379/msjmag.0903RB8029
  DOI ID：10.3379/msjmag.0903RB8029, ISSN：1882-2924, CiNii Articles ID：10025969736, CiNii Books ID：AA12297999
• Room Temperature Ferroelectric and Magnetic Properties of Multiferroic Cobalt Substituted Bi Ferrite Films　　　　　　　　　　　　　　　
  H. Naganuma; J. Miura; K. Kamishima; K. Makizaki; N. Hiratsuka; Y. Ando; S. Okamura
  J. Magn. Soc. Jpn., Volume：33, First page：237, Last page：241, 2009, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.3379/msjmag.0903RC8081
  DOI ID：10.3379/msjmag.0903RC8081
• Thermoelectric property of Nb-doped Sr2FeMoO6 double perovskite oxide　　　　　　　　　　　　　　　
  Hayato Hishinuma; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：55, Number：12, First page：827, Last page：830, Dec. 2008, [Reviewed]
  Sr2FeMo1-xNbxO6 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples were prepared by a conventional ceramic method. The samples were sintered in 3 %H2/N2 gas at 1100°C for 6 hours. Analysis of the X-ray data shows that the samples are of single phase in double perovskite. The magnetization and the conductivity values are found to decrease with increasing x. Whereas, the Seebeck coefficient is found to increase with respect to x in all compounds.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.55.827
  DOI ID：10.2497/jjspm.55.827, ISSN：0532-8799, SCOPUS ID：62649149876
• Annealing temperature dependences of ferroelectric and magnetic properties in polycrystalline co-substituted BiFeO₃ films　　　　　　　　　　　　　　　
  Hiroshi Naganuma; Jun Miura; Mitsumasa Nakajima; Hiromi Shima; Soichiro Okamura; Shintaro Yasui; Hiroshi Funakubo; Ken Nishida; Takashi Iijima; Masaki Azuma; Yasuo Ando; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Japanese Journal of Applied Physics, Volume：47, Number：9 PART 2, First page：7574, Last page：7578, Sep. 2008, [Reviewed]
  Multiferroic Co-substituted BiFeO3 films were fabricated by chemical solution deposition method followed by post deposition annealing at various temperatures. The substitution of cobalt of B-sites for iron in BiFeO3 was promoted at relatively high temperatures. The B-site substitution by cobalt promoted increases in saturation magnetization and spontaneous magnetization. By substitution, leakage current density was suppressed in a high-electric-field region, and ferroelectric hysteresis (P-E) loops became measurable even at room temperature. The optimal annealing temperature for the coexistence of a high remanent polarization and a high remanent magnetization was 923 K having a high B-site substitution ratio of cobalt. © 2008 The Japan Society of Applied Physics.
  Scientific journal
  DOI：https://doi.org/10.1143/JJAP.47.7574
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=55149103742&origin=inward
  DOI ID：10.1143/JJAP.47.7574, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：55149103742
• Crystal structure and physical properties of (Ni,Cu,Zn)Fe2O4-BaTiO3 coexistence material　　　　　　　　　　　　　　　
  永島 義崇; 神島 謙二; 柿崎 浩一; 平塚 信之; 永沼 博; 岡村 総一郎
  Journal of the Magnetics Society of Japan, Volume：32, Number：3, First page：250, Last page：253, May 2008, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.3379/msjmag.32.250
  DOI ID：10.3379/msjmag.32.250
• Ferroelectric and magnetic properties of multiferroic BiFeO₃ based composite films　　　　　　　　　　　　　　　
  Hiroshi Naganuma; Tomosato Okubo; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka; Soichiro Okamura
  IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Volume：55, Number：5, First page：1051, Last page：1055, May 2008, [Reviewed]
  English, Scientific journal
  DOI：https://doi.org/10.1109/TUFFC.2008.755
  DOI ID：10.1109/TUFFC.2008.755
• Tunnel magnetoresistance effect of spinel ferrite with clathrate structure　　　　　　　　　　　　　　　
  Takashi Ikenoya; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：54, Number：6, First page：451, Last page：454, Jun. 2007, [Reviewed]
  SiO2-coated Fe3O4 samples were prepared by the sol-gel processing with several reaction time conditions. The samples were sintered in vacuum at 1000°C for 2 hours. MR ratio became the maximum of 3.6% for 12.9 vol.% SiO2 sample. This value is large compared with that of Fe3O4 reported before. The magnetization and magnetoresistance are saturated at the same magnetic field of about 4 kOe, which suggests that the MR effect is caused by magnetic scattering.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.54.451
  DOI ID：10.2497/jjspm.54.451, ISSN：0532-8799, SCOPUS ID：34548158406
• High frequency properties of Li substituted Co2Z hexagonal ferrites　　　　　　　　　　　　　　　
  Junichi Nakane; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：54, Number：4, First page：232, Last page：235, Apr. 2007, [Reviewed]
  Z-type hexagonal ferrite samples with Ba3Co 2-2xLixFe24+xO41 (x = 0∼ 1.0) were prepared from stoichiometric mixtures of BaCO3, CoO, Li 2Co3 and α-Fe2O3, by calcinning at 1250°C and then sintering at 1275°C. The single phase of the Z-type was confirmed for the crystal structure of these samples with x=0∼0.5 by X-ray diffraction analysis. The sample with x = 0 showed μ' of 8 at 50MHz. The maximum μ' was 24.5 at x = 0.3. The Snoek's product of μ' × fr was 9G Hz at x = O and then increased to 15 GHz at x = 0.1-0.3. The bulk density took a maximum at x = 0.3, and the coercivity had a minimum at x = 0.3. Therfore, high frequency properties of Co2Z ferrite are specifically improved by the Li+-Fe3+ ions substitution with x=0.3.
  Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.54.232
  DOI ID：10.2497/jjspm.54.232, ISSN：0532-8799, SCOPUS ID：34547285674
• Synchrotron X-ray diffraction for pyrolytic magnetic carbon　　　　　　　　　　　　　　　
  K. Kamishima; T. Noda; F. Kadonome; K. Kakizaki; N. Hiratsuka
  Journal of Magnetism and Magnetic Materials, Volume：310, Number：2 SUPPL. PART 2, Mar. 2007, [Reviewed], [Lead, Corresponding]
  We have prepared pyrolytic carbon samples from triethylamine and investigated their magnetic and crystallographic properties. The magnetic property depends on pyrolysis temperatures. A ferromagnetic sample with M = 5 × 10- 1 emu / g was obtained from the pyrolysis products even at room temperature. The synchrotron X-ray diffraction experiments were performed for the pyrolytic carbon samples in order to see the crystal structure of ferromagnetic samples. Diffraction peaks of iron or iron oxides were not observed for the ferromagnetic samples, whereas the major diffraction peak of the intermediate graphite-diamond (IGD) structure was clearly observed for ferromagnetic and nonmagnetic samples. Therefore, the IGD structure is not the direct cause of ferromagnetism. The ferromagnetism may be related to the graphite-like structure. © 2006 Elsevier B.V. All rights reserved.
  Scientific journal
  DOI：https://doi.org/10.1016/j.jmmm.2006.10.325
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33847251680&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33847251680&origin=inward
  DOI ID：10.1016/j.jmmm.2006.10.325, ISSN：0304-8853, SCOPUS ID：33847251680
• Fine structures and magnetic properties of FeCo granular thin films with plasma polymerized (C₄F₈)_n matrix　　　　　　　　　　　　　　　
  K. Kakizaki; S. Yasoshima; K. -K. Choi; K. Kamishima; N. Hiratsuka
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：310, Number：2, First page：E870, Last page：E872, Mar. 2007, [Reviewed]
  In this paper a method for polymerization of fluorocarbon gas in argon plasma to obtain a novel granular structure was reported. We prepared granular films where FeCo fine particles were distributed in plasma-polymerized. uorocarbon matrix by a facing-targets RF magnetron sputtering method, and investigated the correlation between their structures and magnetic properties. The magnetization of the films prepared with the partial pressure of fluorocarbon gas between 0 and 1.0 mTorr decreased linearly, because the FeCo content in a unit volume of a. lm decreased when a polymerized material was used as the matrix. However, the coercivity of the films decreased drastically with increasing the partial pressure of fluorocarbon gas above 0.4 mTorr. This is because the magnetic anisotropy of FeCo particles is decreased by the decrease of grain size. It was confirmed by a TEM observation that the FeCo-(C4F8)(n) films had the granular structure which was constituted by the very fine FeCo particles and the plasma-polymerized fluorocarbon matrix. For the film deposited at the partial pressure of fluorocarbon gas of 0.4 mTorr, the size of FeCo magnetic particles is about 20 nm. On the other hand, the size of FeCo particles is decreased to about 8 nm when the. lm deposited at the partial pressure of fluorocarbon gas of 0.8 mTorr and its distribution is small. (C) 2006 Published by Elsevier B. V.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.mmm.2006.11.133
  DOI ID：10.1016/j.mmm.2006.11.133, ISSN：0304-8853, Web of Science ID：WOS:000247720400422
• High-Frequency Magnetic Characteristics of M-type Barium Ferrites with Substituted Metal Elements　　　　　　　　　　　　　　　
  Miyata K.; Kamishima K.; Kakizaki K.; Hiratsuka N.
  Journal of the Magnetics Society of Japan, Volume：30, Number：3, First page：383, Last page：386, 2006, [Reviewed]
  Co-Zn-Ti substituted M-type barium ferrites of BaCo_xTi_xFe_12-2xO₁₉ (x = 1−3 ) and BaCo_1.1Zn_yTi_1.1+yFe_9.8-2yO₁₉ (y = 0−1.0) were prepared by a powder metallurgy method. Their characteristics were examined by using an X-ray diffractometer, a vibration sample magnetometer (VSM), a vector impedance analyzer, and a scanning electron microscope. When Fe ions of BaFe₁₂O₁₉ were replaced with Co-Ti ions, the magnetic anisotropy and coercivity decreased. As a result, the initial permeability increased to 27 for a sample with x = 1.15. Zn-Ti ions were also substituted for Fe ions in BaCo_1.1Ti_1.1Fe_9.8O₁₉. When the amount of substitution (y) was 0.4 in BaCo_1.1Zn_yTi_1.1+yFe_9.8-2yO₁₉ (y = 0−1.0), the initial permeability at 10 MHz had a very high value of about 40. The reason for this may be that the coercivity becomes small as a result of the growth of the crystal particles and the decrease in the anisotropic magnetic field.
  The Magnetics Society of Japan, Japanese
  DOI：https://doi.org/10.3379/jmsjmag.30.383
  DOI ID：10.3379/jmsjmag.30.383, ISSN：0285-0192, CiNii Articles ID：130004479050
• High frequency properties of soft magnetic ferroxplana type ferrites　　　　　　　　　　　　　　　
  Hitoshi Matsuura; Kenji Kawano; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：53, Number：3, First page：268, Last page：272, 2006, [Reviewed]
  Y-type (Ba2Zn2Fe12O22
  Y), M-type (BaCo1.1Ti1.1Fe9.8O19
  M CT) and mixture of these hexagonal ferrites (Y+xM CT
  x = 0-3) were prepared by the conventional solid-state reaction approach. Samples were made with BaCO3, ZnO, CoO, TiO2 and α-Fe2O3 as starting materials. The frequency dependence of the initial permeability of all samples was measured using an impedance analyzer (HP4291B). The initial permeability of Ba3Zn 2Co1.1Ti1.1Fe21.8O41 (x=1) was 23 (at 100MHz), which is the highest value in this study and the Snoek's product of this sample has been reached to 14.7 GHz. This value is twice larger than that of Zn2Y. The detailed analysis of frequency dependent permeability curves for these samples strongly suggests that this enhancement of the Snoek's product is due to the change of magnetic anisotropy caused by the substitution of Co2+ and Ti4+ ions for Fe3+ ions.
  Funtai Funamtsu Yakin Kyokai/Japan Soc. of Powder Metallurgy, Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.53.268
  DOI ID：10.2497/jjspm.53.268, ISSN：0532-8799, SCOPUS ID：33745017686
• Levitation mechanism of a single steel ball under moderate magnetic fields provided by a Ne-Fe-B ring magnet　　　　　　　　　　　　　　　
  M Sakai; Y Takabayashi; K Sugawara; T Shibayama; Y Shimomura; T Orikasa; K Kamishima; N Hirastuka
  JOURNAL OF APPLIED PHYSICS, Volume：97, Number：8, Apr. 2005, [Reviewed]
  Mechanism for magnetic levitation of a steel ball in a plastic box [S. Sasaki, I. Yagi, and M. Murakami, J. Appl. Phys. 95, 2090 (2004)] was investigated quantitatively based on measurement of the magnetic moments of the steel ball and ring magnet used in levitation experiment. The two-dimensional potential energy calculated in terms of magnetic dipole-dipole interactions gives rise to a stable equilibrium position approximately in agreement with the levitating position observed in our study. The role of the diamagnetic characteristic of the plastic plates was also discussed quantitatively. (C) 2005 American Institute of Physics.
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.1870096
  DOI ID：10.1063/1.1870096, ISSN：0021-8979, Web of Science ID：WOS:000228729500071
• Magnetoresistance in Cu ferrite system　　　　　　　　　　　　　　　
  Keishi Sato; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Volume：51, Number：9, First page：708, Last page：712, 2004, [Reviewed]
  Polycrystalline Cu1-xFe2+xO4 (x=0, 0.25, 0.50, 0.75, 0.90) samples with spinel structure were prepared by the conventional ceramic process. The samples were sintered in N2 at 1100∼1400°C for 2 hours. The resistivity of all the samples is in 10-2 ∼10Ωcm, which is low as a ferrite. This originates in the hopping conduction between Cu1+ and Cu2+, and between Fe2+ and Fe3+ in all the samples. MR ratio at room temperature in Cu0.50Fe2.50O4 became maximum 10.4%. This value is large twice compared with that of Fe3O 4 reported before. The curves of MR and magnetization of Cu 0.50Fe2.50O4 have correlation, in which resistance decreases as magnetization increases. The MR effect is coused by magnetic scattering.
  Journal of the Japan Society of Powder and Powder Metallurgy, Japanese, Scientific journal
  DOI：https://doi.org/10.2497/jjspm.51.708
  DOI ID：10.2497/jjspm.51.708, ISSN：0532-8799, SCOPUS ID：10444265924
• Pressure Induced Magnetic Transition of Mn₃Ga _1-xAl_xC　　　　　　　　　　　　　　　
  Kenji Kamishima; Tsuneaki Goto; Tatsuji Sasaki; Takeshi Kanomata; Toshiya Inami
  Journal of the Physical Society of Japan, Volume：71, Number：3, First page：922, Last page：926, Mar. 2002, [Reviewed], [Lead, Corresponding]
  We have measured the magnetization of Mn3Ga1-xAl xC with x = 0, 0.01 and 0.02 under pressure up to 1.25 GPa. A magnetic transition from an antiferromagnetic (AFM) to an intermediate (IM) state with spontaneous magnetization is observed under pressure. We have determined the phase diagram in the pressure-temperature plane. The application of pressure increases the magnetization in the ferromagnetic (FM) phase for all these compounds. We have also measured the thermal expansion of Mn 3Ga0.97Al0.03C. It is consistent with the pressure effects on the magnetization and suggests the magnetic contribution to the thermal expansion as ωmFM < ω m1M < ωmAFM. Neutron diffraction experiments were performed on Mn3Ga0.95Al 0.05C. Bragg peaks corresponding to an antiferromagnetic component were observed in the IM state. It is highly possible that the IM state has a canted ferromagnetic structure.
  Scientific journal
  DOI：https://doi.org/10.1143/JPSJ.71.922
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  DOI ID：10.1143/JPSJ.71.922, ISSN：0031-9015, SCOPUS ID：0036250879
• Itinerant-electron metamagnetism and magneto-volume effects in Lu(Co_1-xAl_x)₂ Laves phase compounds　　　　　　　　　　　　　　　
  T Yokoyama; H Saito; K Fukamichi; K Kamishima; T Goto; H Yamada
  JOURNAL OF PHYSICS-CONDENSED MATTER, Volume：13, Number：41, First page：9281, Last page：9300, Oct. 2001, [Reviewed]
  The itinerant-electron metamagnetic transition (MT) and the effects of hydrostatic pressure on the critical transition field B-C of the MT, on the spontaneous magnetization M-S and on the Curie temperature T-C have been investigated for well homogenized Lu(Co1-xAlx)(2) Laves phase compounds. The critical field B-C decreases with increasing x, maintaining a linear relationship with the inverse susceptibility at the temperature where the susceptibility exhibits a maximum value, chi (-1) (T-max). On applying pressure, the magnetization M of the ferromagnetic compound with x = 0.100 is drastically decreased at a critical pressure, resulting in a paramagnetic state. In addition, the metamagnetic transition from the paramagnetic to the ferromagnetic state is induced by applying an external magnetic field.
  The effect of pressure on the Curie temperature T-C is extremely large and negative in the vicinity of the critical concentration for the onset of ferromagnetism. The pressure coefficient of the Curie temperature, partial derivative InTC/partial derivativeP, is much larger than that of the spontaneous magnetization, partial derivative InMS/partial derivativeP, below x = 0.150. These results can be explained by the theory for itinerant ferromagnets having a negative coefficient b of the fourth-order term in the Landau expansion. The Landau expansion coefficients estimated from the experimental results are in accord with the theories. From these estimated values, it is concluded that the magneto-volume effect decreases the critical transition field B-C. It has been confirmed that the results for Lu(Co1-xAlx)(2) are very much analogous to those for Lu(Co1-xGax)(2).
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.1088/0953-8984/13/41/317
  DOI ID：10.1088/0953-8984/13/41/317, ISSN：0953-8984, CiNii Articles ID：80012650220, Web of Science ID：WOS:000172033800021
• Investigation of a strong titanium alloy KS15-5-3 and the application to a high pressure apparatus for magnetization measurements　　　　　　　　　　　　　　　
  K. Kamishima; M. Hagiwara; H. Yoshida
  Review of Scientific Instruments, Volume：72, Number：2, First page：1472, Last page：1476, Feb. 2001, [Reviewed], [Lead, Corresponding]
  A β titanium alloy of Ti-15Mo-5Zr-3Al (KS15-5-3) is presented as a new material for experimental apparatus to be used at extreme conditions of high pressure, low temperature, and high magnetic field. The material has a tensile strength of 1760 MPa at room temperature and is found to be a Pauli paramagnet with nearly temperature-independent magnetization M/B∼3 × 10-2 (mJ/Tg)/T, except for TTC. To illustrate the performance of this cell, we present experimental results on a one-dimensional alternating bond antiferromagnet with S = 1:Ni(333-tet)(μ-NO2)(ClO4) [333-tet denotes N,N′-bis(3-aminopropyl)-1,3-propanediamine]. © 2001 American Institute of Physics.
  Scientific journal
  DOI：https://doi.org/10.1063/1.1337074
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0035247169&origin=inward
  DOI ID：10.1063/1.1337074, ISSN：0034-6748, SCOPUS ID：0035247169
• Giant magnetoresistance in the intermetallic compound Mn₃GaC　　　　　　　　　　　　　　　
  K Kamishima; T Goto; H Nakagawa; N Miura; M Ohashi; N Mori; T Sasaki; T Kanomata
  PHYSICAL REVIEW B, Volume：63, Number：2, First page：024426 1-6, Jan. 2001, [Reviewed], [Lead, Corresponding]
  We have measured the transverse resistance of an intermetallic compound Mn3GaC in pulsed high magnetic fields up to 25 T. Giant magnetoresistance is observed due to the field-induced magnetic transition from the antiferromagnetic to the intermediate phase at low temperatures. The temperature dependence of magnetoresistance shows a dip at the Curie temperature. The dip can be explained using a simple model of de Gennes and Friedel based on magnetic critical scatterings. The normal Hall coefficient is found to show a striking change at the transition, suggesting that the giant magnetoresistance is caused by the change of the carrier concentration.
  AMER PHYSICAL SOC, English, Scientific journal
  DOI：https://doi.org/10.1103/PhysRevB.63.024426
  DOI ID：10.1103/PhysRevB.63.024426, ISSN：1098-0121, eISSN：1550-235X, Web of Science ID：WOS:000166382200050
• Giant magnetovolume effect of CrTe　　　　　　　　　　　　　　　
  T Kanomata; Y Sugawara; T Kaneko; K Kamishima; HA Katori; T Goto
  JOURNAL OF ALLOYS AND COMPOUNDS, Volume：297, Number：1-2, First page：5, Last page：8, Feb. 2000, [Reviewed]
  The pressure change of the spontaneous magnetization sigma(s) of the itinerant electron ferromagnet CrTe has been determined in the ranges of hydrostatic pressure and temperature of 0-6.1 kbar and 4.2-70 K, respectively. The spontaneous magnetization decreases linearly with pressure at temperatures from 4.2 to 70 K. The values of d sigma(s)/dp and d In sigma(s)/dp at 4.2 K are found to be -0.92 emu g(-1) kbar(-1) and -1.2x10(-2) kbar(-1), respectively. (C) 2000 Elsevier Science S.A. All rights reserved.
  ELSEVIER SCIENCE SA, English, Scientific journal
  ISSN：0925-8388, Web of Science ID：WOS:000084513000003
• Decoupling of the magnetic ordering of the rare-earth and the Co sublattice in Er_1-xY_xCo₂ compounds driven by substitution or pressure　　　　　　　　　　　　　　　
  R Hauser; E Bauer; E Gratz; H Muller; M Rotter; H Michor; G Hilscher; AS Markosyan; K Kamishima; T Goto
  PHYSICAL REVIEW B, Volume：61, Number：2, First page：1198, Last page：1210, Jan. 2000, [Reviewed]
  The thermodynamic and transport properties of the Er1-xYxCo2 system were studied in the concentration range 0.0 less than or equal to x less than or equal to 1.0: In this system, the first-order magnetic phase transition observed in ErCo2 at T-C = 32 K is related to the itinerant electron metamagnetism of the d subsystem (Co sublattice) driven by the onset of magnetic ordering within the Er sublattice. By employing magnetic, specific heat, thermal expansion, and resistivity measurements we show that in a limited concentration range x(cr') < x < x(cr) and pressure P-cr' < P < P-cr the itinerant Co sublattice orders magnetically at T-C(Co), which is lower than T-C(R) of the Er sublattice. This is referred either to a weakening of the effective molecular field acting on the Co sites owing to the yttrium subsititution or to a pressure-driven increase of the critical field necessary to induce a magnetic moment on the Co sites. On further increasing the yttrium concentration or the pressure only the Er sublattice exhibits long-range order. The theoretical calculations within the molecular field approximation are in agreement with the experimental magnetic x-T phase diagram of the Er1-xYxCo2 system and confirm the effect of a separate ordering of the magnetic sublattices with reasonable parameters used for the intrasublattice Er-Er and intersublattice Er-Co exchange interactions. A field-induced collapse of the Co moment, inverse itinerant electron metamagnetism, is well observable by magnetoresistance measurements at appropriate Values of concentration and external pressure. The existence of itinerant electron metamagnetism in the Co sublattice is found to be limited in temperature by T-0, a characteristic temperature which is sensitive to substitution and pressure.
  AMER PHYSICAL SOC, English, Scientific journal
  ISSN：1098-0121, eISSN：1550-235X, Web of Science ID：WOS:000085760000056
• Itinerant-electron metamagnetism of the Laves-phase compounds Lu(Co_1-xGa_x)₂ under high pressures with high magnetic fields　　　　　　　　　　　　　　　
  H Saito; T Yokoyama; K Fukamichi; K Kamishima; T Goto
  PHYSICAL REVIEW B, Volume：59, Number：13, First page：8725, Last page：8731, Apr. 1999, [Reviewed]
  Magnetic properties of the Laves phase compounds Lu(Co1-xGax)(2) (0.10 less than or equal to x less than or equal to 0.22) have been investigated under the duplicate conditions, i.e., high magnetic fields with high pressures. The pressure effect on the Curie temperature T-C is extremely large in the vicinity of x = 0.10, which is close to the critical concentration for the onset of ferromagnetism. The spontaneous magnetization M-S around x = 0.10 is drastically decreased and a paramagnetic state is induced by applying pressure. The paramagnetic state is changed into a ferromagnetic state by applying magnetic field, accompanied by a metamagnetic transition. The Landau coefficients up to the sixth-order terms of the magnetization for x = 0.10 were estimated from the experimental data. The pressure dependence of the critical transition field H-C for x = 0.10 is consistent with the results calculated from the obtained coefficients. For the compounds with x less than or equal to 0.15, the pressure coefficient of the spontaneous magnetization, partial derivative In M-S / partial derivative P, is much larger than the pressure coefficient of the Curie temperature, partial derivative In T-C / partial derivative P, implying that there is a peak of the density of state just below the Fermi energy. The variation of partial derivative In T-C / partial derivative In M-S as a function of x near the critical concentration of the onset of ferromagnetism can be explained by the theory for itinerant ferromagnets having a negative coefficient b, of the fourth-order term in the Landau expansion. [S0163-1829(99)02413-3].
  AMER PHYSICAL SOC, English, Scientific journal
  ISSN：1098-0121, eISSN：1550-235X, Web of Science ID：WOS:000079754100064
• Magnetic Properties of the 5f Itinerant Electron Metamagnet UCoAl underHigh Pressure　　　　　　　　　　　　　　　
  Mushnikov N.V; T. Goto; K. Kamishima; H. Yamada; A.V. Andreev; Y. Shiokawa; A. Iwao; V. Sechovsky
  Phys. Rev. B, Volume：59, Number：10, First page：6877, Last page：6885, Jan. 1999, [Reviewed]
  English, Scientific journal
  DOI：https://doi.org/10.1103/PhysRevB.59.6877
  DOI ID：10.1103/PhysRevB.59.6877
• Magnetization under high pressure in MnSi　　　　　　　　　　　　　　　
  C Thessieu; K Kamishima; T Goto; G Lapertot
  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：67, Number：10, First page：3605, Last page：3609, Oct. 1998, [Reviewed]
  The magnetization M(H) has been measured in the weakly helimagnetic itinerant compound MnSi under high pressure up to 10.2 kbar and high magnetic field up to 9 Tesla. We interpret the simultaneous decrease under pressure of the saturated magnetization, p(s), and the Curie temper ature: T-c in the frame of the self-consistent renormalization theory (SCR) of spin fluctuations. From the analysis of the so-called Arrott-plot (H/p[H,T] versus p(2)[H,T]) and the respective volume dependence of p(s) and T-c, we estimate the evolution of the characteristic spin fluctua tion temperatures, T-0 and T-A when the system approaches its critical pressure, P-c = 15 kbar, corresponding to the disappearance of the long range magnetic order at T = 0.
  PHYSICAL SOC JAPAN, English, Scientific journal
  ISSN：0031-9015, Web of Science ID：WOS:000076724400047
• Field and pressure dependence of itinerant electrons metamagnetism in Er_1-xY_xCo₂　　　　　　　　　　　　　　　
  AS Markosyan; R Hauser; M Galli; E Bauer; E Gratz; G Hilscher; K Kamishima; T Goto
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：185, Number：2, First page：235, Last page：237, Jun. 1998, [Reviewed]
  By substituting Y for Er in Er1-xYxCo2 the metamagnetic behaviour of the itinerant d subsystem vanishes beyond a critical concentration x(cr) approximate to 0.4. A decoupling of the common magnetic ordering of both magnetic sublattices is observed for x = 0.4 at ambient conditions and for x = 0.3 under pressure. When increasing the pressure beyond a critical value P-cr, only the R subsystem orders in both alloys, whereas the itinerant d sublattice stays disordered down to the lowest temperatures. (C) 1998 Elsevier Science B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0304-8853, Web of Science ID：WOS:000073909200016
• Magnetic Behavior of Mn₃GaC under High Magnetic Field and High Pressure　　　　　　　　　　　　　　　
  Kenji Kamishima; Mikhail I. Bartashevich; Tsuneaki Goto; Makoto Kikuchi; Takeshi Kanomata
  Journal of the Physical Society of Japan, Volume：67, Number：5, First page：1748, Last page：1754, May 1998, [Reviewed], [Lead, Corresponding]
  We have measured the magnetization and magnetostriction of Mn3GaC in pulsed high magnetic fields up to 37 T and the magnetization under steady magnetic field and pressure up to 0.82 GPa. Mn3GaC is antiferromagnetic (AF) at low temperatures. It exhibits successive transitions to an intermediate (I), to a ferromagnetic (F) and to a paramagnetic phase. The transition between the AF and I phases is first order and the others are second order. The transition temperature between the I and F phases does not change greatly with increasing magnetic field. At low temperatures, a metamagnetic transition from the AF to the I state is observed. Volume magnetostriction measurement at 4.2 K indicates that the volume is abruptly decreased by the metamagnetic transition and then gradually shrinks with increasing field. High pressure stabilizes the F phase and enhances the Mn moment.
  Scientific journal
  DOI：https://doi.org/10.1143/JPSJ.67.1748
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0032337451&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0032337451&origin=inward
  DOI ID：10.1143/JPSJ.67.1748, ISSN：0031-9015, SCOPUS ID：0032337451
• High-resolution, high-field magnetization measurement in the diluted antiferromagnet RbMn_cMg_1-cF₃: New application of pulsed high fields to adiabatic magnetization processes　　　　　　　　　　　　　　　
  Y Ajiro; T Asano; H Aruga-Katori; T Goto; K Koui; K Kamishima; H Ikeda
  PHYSICA B, Volume：246, First page：222, Last page：225, May 1998, [Reviewed]
  Tremendously finely resolved magnetization anomalies are reported, for the first time, for pulsed high-field measurements up to 38 T, on the diluted antiferromagnet RbMncMg1-cF3. More than 60 regularly spaced peaks in dM/dB curve are classified into a series of higher harmonics up to sixth order and interpreted in terms of multiple spin flips in the nonequilibrium adiabatic process of the antiferromagnetically coupled Mn2+ dimer system. The result demonstrates an intrigueing potential of application of pulsed high fields to the dynamic magnetization process. (C) 1998 Elsevier Science B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:000074665400045
• High-field magnetization processes of quantum double spin chain systems KCuCl₃, TlCuCl₃ and NH₄CuCl₃　　　　　　　　　　　　　　　
  H Tanaka; W Shiramura; T Takatsu; B Kurniawan; M Takahashi; K Kamishima; K Takizawa; H Mitamura; T Goto
  PHYSICA B-CONDENSED MATTER, Volume：246, First page：230, Last page：233, May 1998, [Reviewed]
  High-field magnetization processes of S = 1/2 double spin chain systems KCuCl3, TiCuCl3 and NH4CuCl3 have been measured up to 39 T at helium temperatures using single crystals. A transition from a singlet ground state with an excitation gap to a gapless magnetic state occurs at H-c similar to 20 and 6 T for KCuCl3 and TlCuCl3, respectively. The excitation gap Delta is evaluated as Delta/kappa(B) = 31.1 K for KCuCl3 and 7.5 K for TlCuCl3. Although the antiferromagnetic interactions in TlCuCl3 are stronger than those in KCuCl3, which can be seen from the slope of the magnetization curves above H-c, the excitation gap in TlCuCl3 is about a quarter of that of KCuCl3. In contrast to KCuCl3 and TlCuCl3, NH4CuCl3 has a gapless magnetic ground state. It is found that NH4CuCl3 undergoes five phase transitions in high magnetic fields. Two wide plateaus are observed at a quarter and three quarters of the saturation magnetization. (C) 1998 Elsevier Science B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:000074665400047
• Magnetovolume Effect of La_0.7Sr_0.3MnO₃　　　　　　　　　　　　　　　
  T. Kanomata; N. Suzuki; K. Kamishima; T. Goto; H. Yoshida; T. Kaneko
  Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu, Volume：7, First page：659, Last page：661, 1998, [Reviewed]
  The magnetization curves at 4.2 K of La0 7Sr0 3MnO3 are obtained under hydrostatic pressure up to 10.1 kbar by employing subtraction magnetometer. The saturation magnetization σ at 4.2 K increases with applied pressure and the pressure dependence of sg is nonlinear. Furthermore, the pressure derivative of the Curie temperature (Tc) of La0 7Sr0 3MnO3 is obtained from the result of measurement of temperature dependence of initial permeability at various pressures. The value of dTcJdp is found to be +0.13 KJkbar. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.
  English, Scientific journal
  DOI：https://doi.org/10.4131/jshpreview.7.659
  DOI ID：10.4131/jshpreview.7.659, ISSN：1348-1940, SCOPUS ID：85024742648
• Magnetic phase diagram of CsNi_1-xFe_xCl₃: magnetization and specific heat　　　　　　　　　　　　　　　
  T Asano; Y Ajiro; M Mekata; K Kamishima; T Goto; HA Katori; K Katsumata
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：177, First page：640, Last page：642, Jan. 1998, [Reviewed]
  Magnetization and specific heat have been measured to determine the magnetic field versus temperature phase diagram of CsNi0.98Fe0.02Cl3. The obtained phase diagram is different from those of the pure CsNiCl3 with easy-axis anisotropy and of CsMnBr3 with strong easy-plane anisotropy, but has features of that predicted for weak easy-plane anisotropy by Plumer et al. A novel phase boundary suggested from neutron diffraction was found to be detectable by magnetization but not by specific heat. (C) 1998 Elsevier Science B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0304-8853, Web of Science ID：WOS:000072262000279
• Pressure effect on spontaneous magnetization of Cr₂Te₃ and Cr₅Te₈　　　　　　　　　　　　　　　
  T Kanomata; Y Sugawara; K Kamishima; H Mitamura; T Goto; S Ohta; T Kaneko
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：177, First page：589, Last page：590, Jan. 1998, [Reviewed]
  The pressure change of the spontaneous magnetization sigma(s), at 4.2 K for Cr2Te3 and Cr5Te8 are measured by employing the subtraction magnetometer. The value of d sigma/dp for Cr2Te3 is -1.22 emu/g kbar. For Cr5Te8, the pressure derivative of sigma(s) is found to be almost zero. (C) 1998 Elsevier Science B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0304-8853, Web of Science ID：WOS:000072262000258
• Instrument for high resolution magnetization measurements at high pressures, high magnetic fields and low temperatures
  K. Koyama; S. Hane; K. Kamishima; T. Goto
  Review of Scientific Instruments, Volume：69, First page：3009, Last page：3014, Jan. 1998, [Reviewed]
  An instrument has been developed for the first time that makes high resolution magnetization measurements at high pressures, high magnetic fields and low temperatures. The instrument consists of an extraction-type magnetometer, a nonmagnetic high pressure clamp cell and a 20 T superconducting magnet with a3He refrigerator and is able to precisely measure the magnetization of weakly magnetic materials. TiCu alloy with 3 wt % Ti is employed as a nonmagnetic material with high mechanical strength for the high pressure clamp cell. This apparatus can be used in the pressure range 0≤P≤13 kbar, the field range 0≤H≤200 kOe and the temperature range 0.5≤T ≤4.2 K. The resolution of the instrument is estimated to be ±0.002 emu. For demonstrating the ability of the instrument, the experimental results on a heavy fermion antiferromagnet Ce7Ni3is presented. © 1998 American Institute of Physics.
  DOI：https://doi.org/10.1063/1.1149048
  DOI ID：10.1063/1.1149048, ISSN：0034-6748, SCOPUS ID：0001379634
• Ground State and Energy Gap of Quantum Double Spin Chain System : KCuCl₃ Family　　　　　　　　　　　　　　　
  W. Shiramura; K. Takatsu; H. Tanaka; K; Takizawa; M; Takahashi; K. Kamishima; H. Mitamura; T. Goto
  Volume：177/181, Number：Pt.1, First page：693, Last page：694, 1998, [Reviewed]
  DOI：https://doi.org/10.1016/S0304-8853(97)00471-X
  DOI ID：10.1016/S0304-8853(97)00471-X, ISSN：0304-8853
• Effect of pressure on Magnetic Properties of Lu(Co_1-xGa_x)₂ Itinerant-electron Ferromagnetic Compounds　　　　　　　　　　　　　　　
  H. Saito; T. Yokoyama; K. Fukamichi; K. Kamishima; H. Mitamura; T. Goto
  Rev. Hight Pressure Sci. Technol., Volume：7, First page：556, Last page：558, 1998
  DOI：https://doi.org/10.4131/jshpreview.7.556
  DOI ID：10.4131/jshpreview.7.556, ISSN：0917-639X
• Effects of alloying and pressure on metamagnetism of UCoAl　　　　　　　　　　　　　　　
  AV Andreev; L Havela; Sechovsky, V; MI Bartashevich; T Goto; K Kamishima
  PHYSICA B, Volume：239, Number：1-2, First page：88, Last page：94, Aug. 1997, [Reviewed]
  Doping by other d-metals in the Co sublattice and/or application of external pressure influences strongly the magnetic properties of 5f-band metamagnet UCoAl. Already 1-2% of Ru or Fe stabilise ferromagnetism, while the doping by Ni as well as the external pressure suppress the metamagnetism. The main role of the observed alloying and pressure effects can be attributed to the involvement of the 5f-ligand hybridisation in both the U 5f-moment formation and the 5f-5f exchange interactions. In many aspects UCoAl shows strong similarities to the 3d band metamagnets CoS2, YCo2 and LuCo2, which suggests an essentially same origin of field-induced phenomena in the both classes of materials.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:A1997XV60900023
• Magnetic behavior of Mn₃Ga_1-xAl_xC under high magnetic field and high pressure　　　　　　　　　　　　　　　
  K Kamishima; T Goto; T Kanomata
  PHYSICA B, Volume：237, First page：561, Last page：562, Jul. 1997
  Mn3GaC is antiferromagnetic (AF) below T-t similar to 160 K and ferromagnetic (F) above T-t. The application of pressure enhances the Mn moment in the F state and produces an intermediate state between the AF and F states. Mn3GaC shows a metamagnetic transition to the F state below T-t. From the transition fields, the electronic specific heat coefficient in the F state is estimated to be gamma = 43 mJ/K-2 mol, which is extremely large. The substitution of Al for Ga in Mn3GaC produces the same effect as the application of high pressure.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/S0921-4526(97)00246-9
  DOI ID：10.1016/S0921-4526(97)00246-9, ISSN：0921-4526, CiNii Articles ID：30003586541, Web of Science ID：WOS:A1997XM23300196
• Crystal lattice changes induced by magnetic field and helifan structure in holmium metal　　　　　　　　　　　　　　　
  H Ohsumi; K Tajima; N Wakabayashi; Y Shinoda; K Kamishima; T Goto
  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：66, Number：7, First page：1896, Last page：1899, Jul. 1997, [Reviewed]
  An X-ray diffraction study has been made on holmium metal in a magnetic field at several temperatures. In most cases, the c-lattice parameter has been observed to change discontinuously with increasing magnetic field, corresponding to the appearance of various magnetic structures. The result or numerical calculations hy a self-consistent mean field method suggests that the effect of the helifan structure on the crystal lattice has been observed in a narrow range of magnetic field.
  PHYSICAL SOC JAPAN, English
  ISSN：0031-9015, Web of Science ID：WOS:A1997XP09400012
• High-field magnetization processes of double spin chain systems KCuCl₃ and TlCuCl₃　　　　　　　　　　　　　　　
  W Shiramura; K Takatsu; H Tanaka; K Kamishima; M Takahashi; H Mitamura; T Goto
  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：66, Number：7, First page：1900, Last page：1903, Jul. 1997, [Reviewed]
  High-field magnetization processes of S=1/2 double spin chain systems KCuCl3 and TlCuCl3 have been measured up to 39 T at 4.2 and 1.7 K for both systems and at 1.0 and 0.5 K for TlCuCl3 using single crystals. A transition from a singlet ground state with an excitation gap to a gapless magnetic state with finite susceptibility occurs at H-c similar to 20 T and 6 T for KCuCl3 and TlCuCl3, respectively. The critical field H-c depends on the external field direction due to the anisotropy of the g-factor. The excitation gap Delta is evaluated as Delta/k(B) = 31.1 K for KCuCl3 and 7.5 K for TlCuCl3. Although the antiferromagnetic interactions in TlCuCl3 are stronger than those in KCuCl3, which can be seen from the slope of the magnetization curves above H-c; the excitation gap in TlCuCl3 is about a quarter of that of KCuCl3. It is observed that the transition field H-c increases with increasing temperature.
  PHYSICAL SOC JAPAN, English
  ISSN：0031-9015, Web of Science ID：WOS:A1997XP09400013
• Anomalous magnetic properties due to Co metamagnetism in Ce(Co_1-xNi_x)₅　　　　　　　　　　　　　　　
  MI Bartashevich; T Goto; K Koui; K Kamishima; AV Korolyov; AS Ermolenko
  PHYSICA B, Volume：237, First page：487, Last page：488, Jul. 1997, [Reviewed]
  The magnetization up to 120 T and 10 kbar and magnetostriction up to 40 T have been measured for single-crystalline Ce(Co1-xNix)(5) with x less than or equal to 0.3. The Co moment is in high moment state for CeCo5 and in low moment state for x greater than or equal to 0.1. A metamagnetic transition from the low to the high moment state can be induced by applying held up to 120 T for x = 0.1 and 0.2. The relations between the Co moment state and the magnetic characteristics are discussed.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:A1997XM23300169
• Magnetic phase transition of MnAs_1-xSb_x　　　　　　　　　　　　　　　
  O Nashima; T Suzuki; K Kamishima; T Goto; H Ido
  PHYSICA B, Volume：237, First page：159, Last page：161, Jul. 1997, [Reviewed]
  Magnetic properties and magnetovolume effects are investigated for MnAs1-xSbx, and all of the experimental data are found to be explained semi-quantitatively on the basis of the Bean-Rodbell model.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:A1997XM23300057
• Singlet ground state and energy gap in double spin chain system KCuCl₃ family　　　　　　　　　　　　　　　
  H Tanaka; K Takatsu; W Shiramura; T Ono; T Kambe; K Kamishima; H Mitamura; T Goto
  PHYSICA B, Volume：237, First page：120, Last page：122, Jul. 1997, [Reviewed]
  Magnetic properties of S = 1/2 double spin chain systems KCuCl3 and TlCuCl3 have been investigated by susceptibility, high-field magnetization process and ESR measurements using single crystals. The present systems can be described as a Heisenberg spin ladder with an additional interaction. It is found that the susceptibilities of both the compounds exhibit broad maxima and decrease exponentially to zero with decreasing temperature. This result indicates that the ground slate of the present system is a spin singlet and there is a finite gap in the excitation spectrum. The transition to the magnetic state is clearly observed by the high-field magnetization process. ESR absorption due to the excitation from the singlet ground state to the excited state is observed for TlCuCl3.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:A1997XM23300045
• 5f band metamagnetism in UCoAl: Effects of alloying and pressure　　　　　　　　　　　　　　　
  AV Andreev; L Havela; Sechovsky, V; MI Bartashevich; T Goto; K Kamishima
  JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Volume：169, Number：3, First page：229, Last page：239, May 1997, [Reviewed]
  We report on the results of magnetisation and susceptibility studies of the effects induced in the 5f band metamagnet UCoAl by doping with other elements and/or by application of external pressure. In majority of aspects UCoAl shows strong similarities to the 3d band metamagnets CoS2, YCo2 and LuCo2, which suggests an essentially same origin of field-induced phenomena in both the classes of materials. The main role of the observed alloying and pressure effects can be attributed to the involvement of the 5f-ligand hybridisation in both the U Sf-moment formation and the 5f-5f exchange interactions.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0304-8853, Web of Science ID：WOS:A1997XE34300001
• Field-induced magnetic transition of Mn₃GaC　　　　　　　　　　　　　　　
  T Kanomata; M Kikuchi; T Kaneko; K Kamishima; MI Bartashevich; HA Katori; T Goto
  SOLID STATE COMMUNICATIONS, Volume：101, Number：11, First page：811, Last page：814, Mar. 1997, [Reviewed]
  Field-induced transitions were studied in Mn3GaC in magnetic fields up to 370 kOe. The antiferromagnetic (AFM)-ferromagnetic (FM) field-induced transition is of the first order. The saturation magnetization sigma(s) at 4.2 K in the FM state is 75.0 emu g(-1) equivalent to 1.1 mu(B) per Mn atom. The decreasing rate of sigma(s) is rather smaller than that of the S = 1/2 Brillouin function. In the magnetostriction measurement of Mn3GaC, an abrupt volume contraction of -0.50% was found at the AFM-FM transition temperature. The result of the forced volume magnetostriction measurement shows that sigma(s) at 4.2 K increases with pressure. (C) 1997 Elsevier Science Ltd.
  PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
  DOI：https://doi.org/10.1016/S0038-1098(96)00737-5
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0031096470&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0031096470&origin=inward
  DOI ID：10.1016/S0038-1098(96)00737-5, ISSN：0038-1098, SCOPUS ID：0031096470, Web of Science ID：WOS:A1997WL29900006
• Effects of external pressure on the 5f-band metamagnetism in UCoAl　　　　　　　　　　　　　　　
  AV Andreev; MI Bartashevich; T Goto; K Kamishima; L Havela; Sechovsky, V
  PHYSICAL REVIEW B, Volume：55, Number：9, First page：5847, Last page：5850, Mar. 1997, [Reviewed]
  UCoAl exhibits below 16 K anisotropic 5f-band metamagnetism induced by magnetic fields as low as similar to 1 T applied along the c axis of the hexagonal structure. No metamagnetic transition is observed in fields up to 40 T applied within the basal plane. The critical field of the metamagnetic transition B-c is composition dependent within the homogeneity range. The metamagnetic transition is found to be very sensitive to external pressure. The value of B-c increases with the rate dB(c)/dp=0.27 T/kbar, whereas the magnetization gained through the transition becomes reduced. The critical pressure of 24 kbar (corresponding to similar to 2% volume contraction) for disappearance of metamagnetism in UCoAl has been estimated. Relations of UCoAl to 3d-band metamagnets are discussed.
  AMERICAN PHYSICAL SOC, English, Scientific journal
  ISSN：0163-1829, Web of Science ID：WOS:A1997WN21800063
• The Haldane state in CsNiCl₃ detected by magnetization measurements - Observation of quantum-classical crossover and the Valence Bond Solid state　　　　　　　　　　　　　　　
  T Asano; Y Ajiro; M Mekata; K Kamishima; K Koui; T Goto; M Furusawa; H Hori
  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：66, Number：2, First page：460, Last page：465, Feb. 1997, [Reviewed]
  We have confirmed from susceptibility and magnetization measurements that the Haldane state really exists in 1D phase of CsNiCl3 which undergoes 3D ordering at T-N = 4.8 K. The observed susceptibility at low fields follows the predicted curve for the S = 1 quantum chain with energy gap (Delta/k(B) similar to 10 K) down to near T-N. A more definite evidence for the Haldane state is given by studying the effect of the nonmagnetic impurities, We haw revealed a real existence of S = 1/2 edge states characteristic of the Haldane state and further revealed a crossover from the quantum to classical regimes as a function of both temperature and field, The result is consistent with the model that at low temperatures (T < T-G Delta/k(B)) and low fields (H < H-G Delta/g mu(B)) the Haldane state is well defined to form the Valence-Bond-Solid while at high temperatures (T > \J\/k(B)) and high fields (H > H-G) the system is not in the Haldane state any more.
  PHYSICAL SOC JAPAN, English, Scientific journal
  ISSN：0031-9015, Web of Science ID：WOS:A1997WR43200038
• 5f-band metamagnetism in UCoAl　　　　　　　　　　　　　　　
  L Havela; AV Andreev; Sechovsky, V; IK Kozlovskaya; K Prokes; P Javorsky; MI Bartashevich; T Goto; K Kamishima
  PHYSICA B, Volume：230, First page：98, Last page：101, Feb. 1997, [Reviewed]
  UCoAl is a 5f-band metamagnet characterized by a very low critical held B-c approximate to 0.8 T, which induces magnetization of 0.3 mu(B)/f.u. by a distinct transition. B-c increases with increasing temperature with the rate consistent with the reduced gamma-coefficient in the high-held state. B-c-values are also sensitive to stoichiometry and external pressure.
  ELSEVIER SCIENCE BV, English, Scientific journal
  ISSN：0921-4526, Web of Science ID：WOS:A1997WW40300028
• Single-Site and Inter-Site Effects in Heavy Fermion Compound CeRu₂Si₂ Studied by Constant Volume Dilution　　　　　　　　　　　　　　　
  K. Matsuhira; T. Sakakibara; H. Amitsuka; K. Tenya; K. Kamishima; T. Goto; G. Kido
  J. Phys. Soc. Jpn., Volume：66, First page：2851, 1997, [Reviewed]
• Magnetovolume Effect of Co₂B　　　　　　　　　　　　　　　
  T. Kanomata; Y. Ise; N. Kumagai; A. Haga; K. Kamishima; T. Goto; H. M. Kimura; H. Yoshida; T. Kaneko; A. Inoue
  Journal of Alloys and Compounds, Volume：259, First page：L1-L4, 1997, [Reviewed]
• Magnetovolume effects of MnAs_1-xSb_x　　　　　　　　　　　　　　　
  O. Nashima; T. Suzuki; H. Ido; K. Kamishima; T. Goto
  Journal of Applied Physics, Volume：79, Number：8 PART 2A, First page：4647, Last page：4649, Apr. 1996
  Thermal expansion, high-field magnetization, and susceptibility measurements have been made for MnAs0.7Sb0.3. The thermal expansion measurements show that the spontaneous magnetostriction is large and anisotropic below Tc. The spontaneous magnetostriction at 0 K is estimated to be 1.2×10-2 for a axis, -0.8×10-2 for c axis, and 1.6×10-2 for the volume. The spontaneous magnetization decreases sharply in the narrow temperature region below Tc=230 K. All the spontaneous magnetostrictions are found to be proportional to the square of spontaneous magnetization. The magnetization curves measured in a high field up to 40 T show the metamagnetic-like transitions at temperatures above Tc, and they are almost perfectly reproduced by an equation H=A1σ+A2σ3+A 3σ5, where H is the applied field and σ is the relative magnetization. © 1996 American Institute of Physics.
  Scientific journal
  DOI：https://doi.org/10.1063/1.361692
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0000042470&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0000042470&origin=inward
  DOI ID：10.1063/1.361692, ISSN：0021-8979, SCOPUS ID：0000042470
• Onset of ferromagnetism between the paramagnets UCoAl and URuAl　　　　　　　　　　　　　　　
  AV Andreev; Sechovsky, V; L Havela; J Sebek; MI Bartashevich; T Goto; K Kamishima; DA Andreev; VS Gaviko; RV Dremov; IK Kozlovskaya
  CZECHOSLOVAK JOURNAL OF PHYSICS, Volume：46, First page：3385, Last page：3386, 1996, [Reviewed]
  Effect of pressure and substitution of Co by Ru on magnetic properties of 5f-band metamagnet UCoAl has been studied. The onset of ferromagnetism between paramagnetic UCoAl and URuAl and strong pressure dependence of parameters of metamagnetic transition in UCoAl have been found.
  CZECHOSLOVAK JNL OF PHYSICS, English, Scientific journal
  ISSN：0011-4626, Web of Science ID：WOS:A1996WH15200078

• チタン酸バリウム構造を含む新規積層結晶構造を用いた磁気トンネル接合材料の創成　　　　　　　　　　　　　　　
  Apr. 2021 - Mar. 2024
  Grant amount(Total)：4030000, Direct funding：3100000, Indirect funding：930000
  Grant number：21K04862
• Use of layered crystal structures for the development of new magnetic-tunnel-junction materials　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Apr. 2016 - Mar. 2019
  Kamishima Kenji, Saitama University
  Grant amount(Total)：4810000, Direct funding：3700000, Indirect funding：1110000
  We have attempted to obtain a bulk material including the sandwich structure made up of two conducting ferromagnetic layers separated by a thin insulating layer. The electric resistance between these ferromagnets will be increased by their antiparallel alignment in magnetization whereas reduced by their parallel alignment, leading to the expectation for application to electronics.
  We succeeded in the synthesis of new materials containing these kinds of layered structures. However, the magnetoresistance was affected by insulating layers between grains out of the crystal structure.
  Grant number：16K04925
• Search for a new biocompatible ferromagnetic material　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Apr. 2012 - Mar. 2015
  KAMISHIMA Kenji, Saitama University
  Grant amount(Total)：4290000, Direct funding：3300000, Indirect funding：990000
  We have attempted to obtain a chemically stable ferromagnet made up of inexpensive and safe elements. The application of sinusoidal magnetic fields can heat a ferromagnet. Therefore, the ferromagnet can be applied to the hyperthermia therapy that uses slightly higher temperatures to give damages to cancer cells.
  We succeeded in synthesis of a potassium lanthanum-iron oxide that had the comparable magnetization with that of iron oxide practical magnets. The magnetization was 59.6 emu/g at room temperature and 96.3 emu/g at 5 K.
  Grant number：24560005
• Preparation of ferromagnetic pyrolytic carbon by heating under magnetic field and its physical properties　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), 2008 - 2010
  KAMISHIMA Kenji, Saitama University
  Grant amount(Total)：3510000, Direct funding：2700000, Indirect funding：810000
  We have prepared pyrolytic carbon samples from triethylamine by pyrolysis under high magnetic field up to 6 Tesla, and investigated their magnetic properties. Ferromagnetic samples were obtained from the pyrolysis products even at room temperature. The maximum spontaneous magnetization was 3.0 emu/g at 300K. The crystal structure was examined by the synchrotron X-ray diffraction experiment at SPring-8. The diffraction peak of diamond was observed for the ferromagnetic samples. Thus, it is possible that the ferromagnetic ordering of radical spins is caused by defects in the diamond structure. The diffraction peak intensity of diamond for the ferromagnetic samples increased with the applied magnetic field at sample preparation. Therefore, the magnetic field may help to form a three dimensional ferromagnetic structure in the carbon-based ferromagnet. A ferromagnetic sample with higher magnetization of 6.4emu/g at 300K was also obtained by field-pyrolysis with diamond powder under magnetic field of 6 Tesla. The crystal growth of the ferromagnetic pyrolytic carbon may be accelerated on the diamond powder, which is consistent with the above-mentioned synchrotron X-ray diffraction result.
  Grant number：20740184