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SAKAI Masamichi
| Mathematics, Electronics and Informatics Division | Professor |
| Department of Electrical Engineering,Electronics, and Applied Physics |
Performance information
■ Paper- Spin injection from a magnetically near-compensated state in GdFeCo and inverse spin Hall effect in electron–hole compensated metal YH2
Ikuo Yamazaki; Yukihiro Koinuma; Tatsuro Hanajiri; Pham Van Thach; Sina Ranjbar; Satoshi Sumi; Hiroyuki Awano; Osamu Nakamura; Shigehiko Hasegawa; Masamichi Sakai
Journal of Physics: Condensed Matter, Volume：37, Number：6, First page：065804, Last page：065804, Nov. 2024, [Reviewed], [Last, Corresponding]
Abstract
Rare-earth–transition-metal (RE–TM) ferrimagnets are excellent materials for spin encode/decode operations via spin transport in nonmagnetic regions. This superior performance stems from two key factors. First, the antiferromagnetic coupling between RE4f and TM3d sublattices reduces both the spin–transfer–torque switching time and inter-device magnetic-coupling. Second, the RE–TM ferrimagnets function as spin injectors/ejectors, with the TM3d sublattice solely responsible for carrier spin polarization (p), similar to conventional ferromagnetic metals. We performed spin transport experiments using the sign change of p in RE–TM, which exhibits a positive value above the magnetization compensation temperature and a negative value below it. We measured temperature dependencies of the transverse resistances ( ) of electron–hole compensated metal YH2 under out-of-plane spin-polarized current injection/ejection from GdFeCo (Gd:Fe:Co = 25:66:9). The abrupt change in loop polarity of the out-of-plane field dependence of in YH2 between 290 and 300 K, which aligns with the out-of-field curve of the polar Kerr rotation in GdFeCo electrodes, strongly suggests that the observed results from the inverse spin Hall effect (ISHE) in YH2. We analytically formulated ISHE in terms of the electron and hole spin currents injected from the spin sources, enabling regression analysis to assess the spin transport characteristics of a GdFeCo/YH2/GdFeCo magnetic double heterostructure. To explain the observed Hall voltages, enhancements in both the spin diffusion length of YH2 and the spin injection efficiency are necessary.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/1361-648x/ad9371
DOI ID：10.1088/1361-648x/ad9371, ISSN：0953-8984, eISSN：1361-648X - Long-distance spin communication via ambipolar conductor with electron–hole spin exchange interaction
Yukihiro Koinuma; Shigehiko Hasegawa; Masamichi Sakai
Journal of Physics: Condensed Matter, Volume：36, Number：13, First page：135806, Jan. 2024, [Reviewed], [Last, Corresponding]
Abstract
Spin accumulation in a nonmagnetic (N) metal embedded between two ferromagnetic metals is still crucial in current spintronics because long-distance spin communication via the N metal can make all-spin logic (ASL) devices feasible. Graphene is almost the only N-region material suitable for ASL devices because its low intrinsic spin–orbit coupling results in a spin diffusion length, , of over 30 µm at room temperature, but long-distance spin communication beyond remains difficult. The present study proposes a way to remove the restriction caused by . In our proposal, an ambipolar conductor, in which electron and hole contribute to electronic conduction and interact with each other, is used for the N-region in a double-heterojunction magnetic structure. When the electron–hole interaction is accompanied by spin exchange, long-distance spin communication characteristic is predicted. Approximately 70 types of ambipolar conductors, including elemental metals and metal alloys, are available. Hence, this material variation may open a new spintronics field, ambipolar spintronics, which may realize operation mechanisms that cannot be achieved using conventional single-band metals. Finally, we present a comprehensive argument on the interface-mediated coupling mechanism between spins and charges, which is the basis of the generation of the spin-coupled interface voltage.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/1361-648x/ad17a5
DOI ID：10.1088/1361-648x/ad17a5, ISSN：0953-8984, eISSN：1361-648X - Spin-charge-coupled transverse resistance in an ambipolar conductor YH2-based Hall-bar structure with perpendicularly magnetized current-injection electrodes
Kaname Sato; Yutaro Takahashi; Shujiro Akisato; Ryota Mikami; Nao Suganuma; Yugo Ashizawa; Hayate Kawaguchi; Yoshikata Nakajima; Tomofumi Ukai; Yasuhiko Fuji; Tatsuro Hanajiri; Junya Kaneko; Osamu Nakamura; Pham Van Thach; Hiroyuki Awano; Shigehiko Hasegawa; Masamichi Sakai
Physica Scripta, Volume：98, Number：4, First page：045912, Last page：045912, Mar. 2023, [Reviewed], [Last, Corresponding]
Abstract
Spin-charge (SC) coupling is crucial in spintronics and the coupling mechanisms can be classified into bulk characteristic via spin-orbit interaction (SOI) or the interfacial characteristic provided by a junction formed by magnetic and nonmagnetic conductors. The two types of SC couplings account for the transverse resistance (TR) in a planer channel subjected to out-of-plane-polarized spin current injection. This is because interfacial spin-accumulation induces the diffusive transport of spin-angular momentum, which is converted into transverse charge accumulation via SOI. We explore the SC coupling characteristics of a lateral junction consisting of (i) a rare-earth transition metal (RE-TM) ferrimagnet with perpendicular magnetic anisotropy and (ii) a compensated metal, YH2, where electrons and holes simultaneously participate in spin and charge transports. This set-up allows us to observe the TR, which mirrors the magnetization of the RE-TM employed as the current-source electrode in the planer Hall-bar structure. The results show that the inverse spin Hall effect contributes significantly to the TR. Along with the TR measurement, we formulate a minimal expression of the TR when out-of-plane-polarized electron and hole spin currents are injected from the magnetic electrode. Since this formulation is independent of the details of the SC coupling mechanism, it is applied to interpret the observation result to reveal the SC coupling characteristics of the RE-TM and YH2 set-up.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/1402-4896/acc4f2
DOI ID：10.1088/1402-4896/acc4f2, ISSN：0031-8949, eISSN：1402-4896 - Hall effect in ytterbium hydrides
Satoru Kitsunai; Daiki Fujii; Toshihiro Yoshizumi; Shigehiko Hasegawa; Osamu Nakamura; Masamichi Sakai
Physics Letters A, Volume：419, First page：127740, Last page：127740, Dec. 2021, [Reviewed], [Last, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physleta.2021.127740
DOI ID：10.1016/j.physleta.2021.127740, ISSN：0375-9601 - Spatiotemporal characteristics of spin transport in compensated metals with electron–hole exchange interaction
Masamichi Sakai; Mst Sanjida Aktar; Toshihiro Yoshizumi; Shigehiko Hasegawa
Journal of Physics: Condensed Matter, Volume：34, Number：5, First page：055801, Nov. 2021, [Reviewed], [Lead, Corresponding]
Abstract
We develop a theory describing spatiotemporal behavior of spin transport in two-band metals by postulating a spin–exchange interaction between electrons and holes. Starting with the semiclassical Boltzmann equation, we derive a system of coupled diffusion equations and solve them analytically under steady-state conditions. The solutions reveal two types of electron–hole coupled-spin transport modes: a dissipative mode and a nondissipative mode with an infinite spin diffusion length. The two modes are the manifestations of two types of spin coupling channels. Besides the exchange interaction, we incorporate into our derivation the relaxation caused by the spin–orbit interaction to show how it affects the spin transport characteristics of the two modes.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/1361-648x/ac327e
DOI ID：10.1088/1361-648x/ac327e, ISSN：0953-8984, eISSN：1361-648X - Nanoparticulate Pt-catalyzed hydrogenation of Yb films: Towards hydrides with higher hydrogen compositions
Toshihiro Yoshizumi; Keigo Koshiba; Satoru Kitsunai; Teru Yoshizawa; Osamu Nakamura; Masamichi Sakai
Chemical Physics, Volume：544, First page：111121, Last page：111121, Apr. 2021, [Reviewed], [Last, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.chemphys.2021.111121
DOI ID：10.1016/j.chemphys.2021.111121, ISSN：0301-0104 - Magneto-transport properties in fcc ytterbium
Toshihiro Yoshizumi; Daiki Fujii; Satoru Kitsunai; Kousuke Igarashi; Masamichi Sakai; Osamu Nakamura; Shigehiko Hasegawa
Physics Letters A, Volume：384, Number：26, First page：126661, Sep. 2020, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physleta.2020.126661
DOI ID：10.1016/j.physleta.2020.126661, ISSN：0375-9601 - Spin and charge transports with thermodynamic electron–hole correlation in nearly compensated metals
Mst. Sanjida Aktar; Masamichi Sakai; Toshihiro Yoshizumi; Shigehiko Hasegawa
AIP Advances, Volume：10, Number：7, Jul. 2020, [Reviewed], [Corresponding]
The long spin-relaxation time (τs) toward the large transport distance of spin current (SC) is desirable for practical applications of spintronic devices because spatially and temporally large spin coherence makes spin manipulation easier. Here, we propose that nearly compensated metals (CMs) with electron–hole collisions accompanied by spin flipping have a potential mechanism that makes τs associated with the antiparallel SC extraordinarily long, where antiparallel SC is defined as the vector subtraction of hole and electron SCs. The present theoretical study on spin and charge transports in nearly CMs shows that (i) it is antiparallel SC that satisfies the Onsager reciprocal relation in combination with conventional charge current, (ii) both longitudinal and Hall resistivities are influenced by the enhancement of τs and are classified into two specific mechanisms, i.e., the conventional and the resonance Hall effect accompanied by a sustaining mode of antiparallel SC, and (iii) the resonance Hall effect is not influenced by the spin–orbit interaction unlike the non-resonance case. These findings indicate the potential of nearly CMs in application of spintronic materials.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/5.0013628
DOI ID：10.1063/5.0013628, eISSN：2158-3226 - Entropy production by thermodynamic currents in ambipolar conductors with identical spin dynamics characteristics between holes and electrons
Mst. Sanjida Aktar; Masamichi Sakai; Shigehiko Hasegawa; Osamu Nakamura; Hiroyuki Awano
Applied Physics Express, Volume：12, Number：5, First page：053004, Apr. 2019, [Reviewed], [Corresponding]
IOP Publishing, Scientific journal
DOI：https://doi.org/10.7567/1882-0786/ab101e
DOI ID：10.7567/1882-0786/ab101e, ISSN：1882-0778, eISSN：1882-0786 - Low-temperature synthesis of hydride semiconductor YH3−δ using Pt capped Y films and its chemical thermodynamics analysis
T. Sakai; M. Sakai; T. Kobayashi; M. Yasutake; S. Akisato; R. Mikami; N. Suganuma; Y. Takahashi; Y. Nakajima; M. Tokuda; Y. Fujii; T. Hanajiri; O. Nakamura
Thin Solid Films, Volume：669, First page：288, Last page：293, Jan. 2019, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.tsf.2018.10.054
DOI ID：10.1016/j.tsf.2018.10.054, ISSN：0040-6090 - Resonant Hall effect under generation of a self-sustaining mode of spin current in nonmagnetic bipolar conductors with identical characters between holes and electrons
Masamichi Sakai; Hiraku Takao; Tomoyoshi Matsunaga; Makoto Nishimagi; Keitaro Iizasa; Takahito Sakuraba; Koji Higuchi; Akira Kitajima; Shigehiko Hasegawa; Osamu Nakamura; Yuichiro Kurokawa; Hiroyuki Awano
Japanese Journal of Applied Physics, Volume：57, Number：3, Mar. 2018, [Reviewed], [Lead, Corresponding]
We have proposed an enhancement mechanism of the Hall effect, the signal of which is amplified due to the generation of a sustaining mode of spin current. Our analytic derivations of the Hall resistivity revealed the conditions indispensable for the observation of the effect: (i) the presence of the transverse component of an effective electric field due to spin splitting in chemical potential in addition to the longitudinal component
(ii) the simultaneous presence of holes and electrons each having approximately the same characteristics
(iii) spin-polarized current injection from magnetized electrodes
(iv) the boundary condition for the transverse current (J c, y = 0). The model proposed in this study was experimentally verified by using van der Pauw-type Hall devices consisting of the nonmagnetic bipolar conductor YH x (x ≃ 2) and TbFeCo electrodes. Replacing Au electrodes with TbFeCo electrodes alters the Hall resistivity from the ordinary Hall effect to the anomalous Hall-like effect with an enhancement factor of approximately 50 at 4 T. We interpreted the enhancement phenomenon in terms of the present model.
Japan Society of Applied Physics, English, Scientific journal
DOI：https://doi.org/10.7567/JJAP.57.033001
DOI ID：10.7567/JJAP.57.033001, ISSN：1347-4065, SCOPUS ID：85042653338, Web of Science ID：WOS:000424666300001 - Fabrication of YH3 thin film using Pd/Ni co-capping layer: Ni thickness effect
K. Yabuki; H. Hirama; N. Aoki; M. Sakai; Y. Saito; K. Higuchi; A. Kitajima; S. Hasegawa; O. Nakamura
Journal of Crystal Growth, Volume：468, First page：714, Last page：717, Jun. 2017, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jcrysgro.2016.10.001
DOI ID：10.1016/j.jcrysgro.2016.10.001, ISSN：0022-0248 - Purification of commercial yttrium metal: Removal of fluorine
A. Takenouchi; T. Otomo; K. Niwa; M. Sakai; Y. Saito; T. Kirigane; M. Kosaka; S. Michimura; S. Hasegawa; O. Nakamura
Journal of Crystal Growth, Volume：468, First page：701, Last page：704, Jun. 2017, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jcrysgro.2016.11.091
DOI ID：10.1016/j.jcrysgro.2016.11.091, ISSN：0022-0248 - Phthalocyanine based metal containing porous carbon sheet
Z. Honda; Y. Sakaguchi; M. Tashiro; M. Hagiwara; T. Kida; M. Sakai; T. Fukuda; N. Kamata
Applied Physics Letters, Volume：110, Number：13, Mar. 2017, [Reviewed]
Highly-ordered fused-ring poly copper phthalocyanine (PCuPc) was prepared using copper octacyanophthalocyanine as a building block, and two-dimensional (2D) square superlattices were directly observed by the transmission electron microscopy. Remarkably, we have found a formation of polymer network that consists of a 2D porous PCuPc sheet in which the centers of phthalocyanine units are alternately occupied by Cu atom and vacancy. Using this “half-filling” PCuPc, it must be possible to create alternating arrangements for transition metal centers, and therefore control the magnetic properties of the 2D carbon sheets.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.4979030
DOI ID：10.1063/1.4979030, ISSN：0003-6951, eISSN：1077-3118 - Crystal structures and magnetic properties of the honeycomb-lattice antiferromagnet M2(pymca)3(ClO4), (M = Fe, Co, Ni)
Zentaro Honda; Takafumi Kodama; Masayuki Hagiwara; Takanori Kida; Akira Okutani; Masamichi Sakai; Takeshi Fukuda; Norihiko Kamata
Solid State Sciences, Volume：59, First page：15, Last page：18, Sep. 2016, [Reviewed]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.solidstatesciences.2016.07.002
DOI ID：10.1016/j.solidstatesciences.2016.07.002, ISSN：1293-2558 - Preparation and magnetic properties of phthalocyanine-based carbon materials containing transition metals
Z. Honda; S. Sato; M. Hagiwara; T. Kida; M. Sakai; T. Fukuda; N. Kamata
Journal of Applied Physics, Volume：120, Number：2, Jul. 2016, [Reviewed]
A simple method for the preparation of bulk quantities of magnetic carbon materials, which contain uniformly dispersed transition metals (M = Fe, Co, Ni, and Cu) as the magnetic components, is presented. By using highly chlorinated metal phthalocyanine as the building block and potassium as the coupling reagent, phthalocyanine-based carbon materials (PBCMs) containing transition metals were obtained. Our experiments demonstrate the structure of these PBCMs consists of transition metals embedded in graphitic carbon that includes a square planar MN4 magnetic core and the Fe and Co-PBCM possess spontaneous magnetization at room temperature. In addition, carbon-coated transition metal particles were obtained by the Wurtz-type reaction with excess amount of potassium coupling agent. The large transition metal surface area and magnetization of these M-PBCMs are useful for spintronic and catalytic applications.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.4956344
DOI ID：10.1063/1.4956344, ISSN：0021-8979, eISSN：1089-7550 - Macroscopic kinematics of the Hall electric field under influence of carrier magnetic moments
Masamichi Sakai
AIP Advances, Volume：6, Number：6, Jun. 2016, [Reviewed], [Lead, Corresponding]
The relativistic effect on electromagnetic forces yields two types of forces which depend on the velocity of the relevant particles: (i) the usual Lorentz force exerted on a moving charged particle and (ii) the apparent Lorentz force exerted on a moving magnetic moment. In sharp contrast with type (i), the type (ii) force originates due to the transverse field induced by the Hall effect (HE). This study incorporates both forces into a Drude-type equation with a fully spin-polarized condition to investigate the effects of self-consistency of the source and the resultant fields on the HE. We also examine the self-consistency of the carrier kinematics and electromagnetic dynamics by simultaneously considering the Drude type equation and Maxwell equations at low frequencies. Thus, our approach can predict both the dc and ac characteristics of the HE, demonstrating that the dc current condition solely yields the ordinary HE, while the ac current condition yields generation of both fundamental and second harmonic modes of the HE field. When the magnetostatic field is absent, the simultaneous presence of dc and ac longitudinal currents generates the ac HE that has both fundamental frequency and second harmonic.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.4954808
DOI ID：10.1063/1.4954808, eISSN：2158-3226 - 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, Oct. 2015, [Reviewed]
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∘C. The spontaneous magnetization at 5 K was 44.2 μB/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 Néel-type collinear ferrimagnetic structure. The Curie temperature of the Sr2Ni2X-type hexaferrite was estimated to be TC[Sr2Ni2X] = 472∘C. This is consistent with the difference of the block stacking structures of SrM-type, Sr2Ni2X-type, SrNi2W-type, and nickel spinel ferrites.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.4934792
DOI ID：10.1063/1.4934792, eISSN：2158-3226 - Crystal Structure of the Spin 1/2 Honeycomb-Lattice Antiferromagnet Cu2(pymca)3(ClO4)
Zentaro Honda; Takafumi Kodama; Reo Kikukawa; Masayuki Hagiwara; Takanori Kida; Masamichi Sakai; Takeshi Fukuda; Takashi Fujihara; Norihiko Kamata
Journal of the Physical Society of Japan, Volume：84, Number：3, First page：034601, Mar. 2015, [Reviewed], [Last]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.7566/jpsj.84.034601
DOI ID：10.7566/jpsj.84.034601, ISSN：0031-9015, eISSN：1347-4073 - 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]
Elsevier BV, 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 - Hall resistivity and transverse magnetoresistivity generated in simultaneous presence of spin-polarized current and external magnetic field in a nonmagnetic bipolar conductor YH2
Masamichi Sakai; Hiraku Takao; Tomoyoshi Matsunaga; Yusuke Tanaka; Tatsuya Arai; Shota Haruyama; Takashi Otomo; Hiroaki Hirama; Takahito Sakuraba; Zentaro Honda; Koji Higuchi; Akira Kitajima; Akihiro Oshima; Shigehiko Hasegawa; Hiroyuki Awano
Japanese Journal of Applied Physics, Volume：54, Number：1, First page：013001, Dec. 2014, [Reviewed], [Lead, Corresponding]
IOP Publishing, Scientific journal
DOI：https://doi.org/10.7567/jjap.54.013001
DOI ID：10.7567/jjap.54.013001, ISSN：0021-4922, eISSN：1347-4065 - 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]
Elsevier BV, 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 - Room temperature ferromagnetism in a phthalocyanine based carbon material
Z. Honda; K. Sato; M. Hagiwara; T. Kida; M. Sakai; T. Fukuda; N. Kamata
Journal of Applied Physics, Volume：115, Number：5, Feb. 2014, [Reviewed]
We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at Tc = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.4863539
DOI ID：10.1063/1.4863539, ISSN：0021-8979, eISSN：1089-7550 - Influence of hydrogen incorporation on texture and grain size in YH2 films
T. Okoshi; M. Hayakawa; H. Hirama; M. Sakai; K. Higuchi; A. Kitajima; A. Oshima; S. Hasegawa
Journal of Crystal Growth, Volume：378, First page：388, Last page：392, Sep. 2013, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.093
DOI ID：10.1016/j.jcrysgro.2012.12.093, ISSN：0022-0248 - Crystal growth of magnetic dihydride GdxY1−xH2 for generation of spin current
T. Sakuraba; H. Hirama; M. Sakai; Z. Honda; M. Hayakawa; T. Okoshi; A. Kitajima; A. Oshima; K. Higuchi; S. Hasegawa
Journal of Crystal Growth, Volume：378, First page：351, Last page：355, Sep. 2013, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.156
DOI ID：10.1016/j.jcrysgro.2012.12.156, ISSN：0022-0248 - Enhancement of hydrogen uptake for Y and Gd films by thin Ni surface overlayers
H. Hirama; M. Hayakawa; T. Okoshi; M. Sakai; K. Higuchi; A. Kitajima; A. Oshima; S. Hasegawa
Journal of Crystal Growth, Volume：378, First page：356, Last page：360, Sep. 2013, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.175
DOI ID：10.1016/j.jcrysgro.2012.12.175, ISSN：0022-0248 - Magnetoresistance Generated by Combination of Spin-Orbit Interaction and Applied Magnetic Field in Bipolar Conductors
Masamichi Sakai; Daisuke Kodama; Yoshihisa Okano; Takahito Sakuraba; Zentaro Honda; Akira Kitajima; Akihiro Oshima; Koji Higuchi; Shigehiko Hasegawa; Osamu Nakamura
JAPANESE JOURNAL OF APPLIED PHYSICS, Volume：52, Number：9, Sep. 2013, [Reviewed], [Lead, Corresponding]
We have theoretically studied the magnetotransport properties in bipolar conductors under consideration of the simultaneous presence of an external magnetic field, left-right asymmetric carrier scattering due to spin-orbit interactions, and spin-polarized holes/electrons, predicting both positive and negative transverse magnetoresistance (TMR) terms, the mechanisms of which are completely different from the conventional mechanism in bipolar conductors. The positive TMR term is predicted only for the asymmetric carrier scattering case, the sign of which is the same (negative) between a hole and an electron. The other case of asymmetric scattering, the sign of which is opposite between a hole and an electron, was also determined to always show a negative TMR. Our proposed TMR was experimentally evidenced from the magnetotransport and magnetization measurements of a compensated metal, YH2. Also, application to logic gates is discussed on the basis of our proposed mechanism. (C) 2013 The Japan Society of Applied Physics
IOP PUBLISHING LTD, English, Scientific journal
DOI：https://doi.org/10.7567/JJAP.52.093001
DOI ID：10.7567/JJAP.52.093001, ISSN：0021-4922, eISSN：1347-4065, Web of Science ID：WOS:000323884300022 - 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. Japan, Volume：38, Number：3, First page：451, Last page：454, 2013, [Reviewed] - Synthesis of a new U-type hexaferrite Ba<sub>4</sub>Cu<sub>2</sub>Fe<sub>36</sub>O<sub>60</sub>
Ryumon Tajima; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratsuka; Atsuhiro Fujimori; Masamichi Sakai; Kowashi Watanabe
Transactions of the Materials Research Society of Japan, Volume：38, Number：3, First page：451, Last page：454, 2013, [Reviewed]
The Materials Research Society of Japan, Scientific journal
DOI：https://doi.org/10.14723/tmrsj.38.451
DOI ID：10.14723/tmrsj.38.451, ISSN：1382-3469, eISSN：2188-1650 - Design of Spin Polarization Analyzer using Transverse-Longitudinal Correlation in Resistivities Induced by Spin–Orbit Interaction
Masamichi Sakai; Koichi Kakizaki; Shigehiko Hasegawa; Akira Kitajima; Akihiro Oshima; Hiroyuki Awano
Japanese Journal of Applied Physics, Volume：52, Number：1R, First page：013004, Last page：013004, Dec. 2012, [Reviewed], [Lead, Corresponding]
We have theoretically studied a methodology for the measurement of the degree of spin polarization (P) in metals as well as semiconductors. Our principle is based on the correlation existing between transverse resistivity (ρ y x ) and longitudinal resistivity (ρ x x ), both influenced by transverse scattering due to a spin–orbit interaction (SOI) as well as longitudinal scattering due to usual mechanisms. Our spin polarization analyzer employs an unknown polarization conductor as a source electrode from which spin-polarized electrons are injected into a nonmagnetic (NM) channel region. The channel length is set to be much smaller than its spin diffusion length so that ρ y x and ρ x x in the NM region, both complementarily influenced by carrier spin polarization, would be measured to obtain the P value. Also, application to OR and XOR logic gates are discussed on the basis of our spin polarization analyzer.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.7567/jjap.52.013004
DOI ID：10.7567/jjap.52.013004, ISSN：0021-4922, eISSN：1347-4065 - Magnetic Field-Induced Phase Transitions in the S=1/2 Two-Leg Spin-Ladder Material Cu(DEP)Br-2
Honda Zentaro; Katori Hiroko Aruga; Ikeda Masami; Hagiwara Masayuki; Okunishi Kouichi; Sakai Masamichi; Fukuda Takeshi; Kamata Norihiko
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Volume：81, Number：11, Nov. 2012, [Reviewed]
DOI：https://doi.org/10.1143/JPSJ.81.113710
DOI ID：10.1143/JPSJ.81.113710, ISSN：0031-9015, Web of Science ID：WOS:000310509600013 - High-Field Magnetization of the S=1/2 Two-Leg Spin-Ladder Antiferromagnets CuAX2 (A=Diazine, X=Halogen)
M. Ikeda; Z. Honda; M. Sakai; S. Kimura; K. Okunishi; M. Hagiwara
Journal of Low Temperature Physics, Volume：170, Number：5-6, First page：296, Last page：301, Oct. 2012, [Reviewed]
Springer Science and Business Media LLC, Scientific journal
DOI：https://doi.org/10.1007/s10909-012-0809-y
DOI ID：10.1007/s10909-012-0809-y, ISSN：0022-2291, eISSN：1573-7357 - Negative Magnetoresistance Generated by Combination of Spin-Orbit Interaction and Applied Magnetic Field
Masamichi Sakai; Daisuke Kodama; Takahito Sakuraba; Zentaro Honda; Shigehiko Hasegawa; Akira Kitajima; Akihiro Oshima; Koji Higuchi; Osamu Nakamura
JAPANESE JOURNAL OF APPLIED PHYSICS, Volume：51, Number：2, Feb. 2012, [Reviewed], [Lead, Corresponding]
We have theoretically studied a negative magnetoresistance (MR) the mechanism of which is completely different from conventional mechanisms, i.e., spin-related mobility-increased mechanisms and orbital-motion-related mechanisms including a quantum interference effect. Our proposed negative MR is caused by the interplay between a spin-orbit interaction (SOI) and the Lorentz force due to an externally applied magnetic field. We have phenomenologically approached this mechanism using the Drude-like model, in which the carrier scattering by SOI is considered as a transverse scattering term in addition to the longitudinal scattering term due to usual collisions and the Lorentz force term. Also, the possibility of observing our proposed negative MR was discussed by comparing our prediction with experimental results for Ni and Gd films, which were newly measured in this study. (C) 2012 The Japan Society of Applied Physics
JAPAN SOC APPLIED PHYSICS, English, Scientific journal
DOI：https://doi.org/10.1143/JJAP.51.023001
DOI ID：10.1143/JJAP.51.023001, ISSN：0021-4922, Web of Science ID：WOS:000300627200035 - Tunneling Magnetoresitance in BaTiO3/Fe3O4 composites, Trans. Mat. Res. Soc. Japan 37[2], 275-278 (2012).
T. Noshiro; K. Kamishima; K. Kakizaki; N. Hiratuka; M. Sakai; Kowashi Watanabe
Trans. Mat. Res. Soc. Japan, Volume：37, Number：2, First page：275, Last page：278, 2012, [Reviewed] - Tunneling magnetoresistance in BaTiO<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> composites
Tomoya Noshiro; Kenji Kamishima; Koichi Kakizaki; Nobuyuki Hiratuka; Masamichi Sakai; Kowashi Watanabe
Transactions of the Materials Research Society of Japan, Volume：37, Number：2, First page：275, Last page：278, 2012, [Reviewed]
The Materials Research Society of Japan, Scientific journal
DOI：https://doi.org/10.14723/tmrsj.37.275
DOI ID：10.14723/tmrsj.37.275, ISSN：1382-3469, eISSN：2188-1650 - Generation of Spin Current in Bipolar Conductors
Masamichi Sakai; Takahito Sakuraba; Zentaro Honda; Shigehiko Hasegawa; Akira Kitajima; Koji Higuchi; Akihiro Oshima; Osamu Nakamura
JAPANESE JOURNAL OF APPLIED PHYSICS, Volume：50, Number：10, Oct. 2011, [Reviewed], [Lead, Corresponding]
The ordinary Hall effect (OHE), which is caused by an external magnetic field, was studied as a mechanism for the generation of spin current. It has been theoretically elucidated that, under an open-circuit condition, the OHE can contribute to spin-current generation when spin-polarized electrons and holes are simultaneously present as mobile carriers. This OHE contribution to spin current generation is caused by the steady-state kinematics of electrons and holes whose transverse velocities have the same direction. Although anomalous Hall effects may contribute to spin-current generation, the OHE plays a principal role in the generation of spin current when electrons and holes have approximately the same transport characteristics. The experimental aspects of possible materials for the isomorphic electron and hole systems are argued on the basis of the experimental results of the magnetotransport measurement of yttrium dihydride and preliminary results of the magnetization measurement of hydrogenated films of gadolinium. (C) 2011 The Japan Society of Applied Physics
JAPAN SOC APPLIED PHYSICS, English, Scientific journal
DOI：https://doi.org/10.1143/JJAP.50.103002
DOI ID：10.1143/JJAP.50.103002, ISSN：0021-4922, Web of Science ID：WOS:000296085700041 - Thermoelectric Properties of Double Perovskite (Sr, Ba)2(Fe, Mn)(Mo, V)O6
Ayaka Oba; Kenji Kamishima; Koichi Kakizaki; Yoshihiro Ishimaru; Masamichi Sakai; Nobuyuki Hiratsuka
Journal of the Japan Society of Powder and Powder Metallurgy, Volume：58, Number：6, First page：374, Last page：379, 2011, [Reviewed]
Japan Society of Powder and Powder Metallurgy, Scientific journal
DOI：https://doi.org/10.2497/jjspm.58.374
DOI ID：10.2497/jjspm.58.374, ISSN：0532-8799, eISSN：1880-9014 - 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
Journal of the Japan Society of Powder and Powder Metallurgy, Volume：58, Number：6, First page：334, Last page：339, 2011, [Reviewed], [Last]
Japan Society of Powder and Powder Metallurgy, Scientific journal
DOI：https://doi.org/10.2497/jjspm.58.334
DOI ID：10.2497/jjspm.58.334, ISSN：0532-8799, eISSN：1880-9014 - Appearance of a correlation between the Hall coefficient and electrical resistivity upon dihydrogenation of yttrium
M. Sakai; D. Kodama; S. Ito; M. Ito; O. Nakamura; S. Hasegawa; A. Kitajima; A. Oshima
Journal of Applied Physics, Volume：108, Number：8, Oct. 2010, [Reviewed], [Lead, Corresponding]
To shed light on the correlation between the Hall coefficient (RH) and electrical resistivity (ρ), we performed simultaneous measurements of these two transport coefficients in fcc dihydride phase of yttrium (YHx), having H/Y values ranging from 1.73 to 2.04. Unlike the typical behavior of metals, an approximately linear relationship was observed between RH and ρ at room temperature after dihydrogenation of yttrium. Interpretation of this relationship, based on the Boltzmann–Bloch scheme, reveals that the transverse (cyclotron) relaxation rate (1/τc) of the carriers is relatively insensitive to the generation of hydrogen defects in the dihydride phase of yttrium, unlike the longitudinal relaxation rate (1/τ), which is affected by the presence of hydrogen defect. Low-temperature (77 K) measurements of RH and ρ on the same samples show that the approximately linear relationship observed at room temperature disappears but a certain nonlinear relationship may exist at 77 K.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.3500443
DOI ID：10.1063/1.3500443, ISSN：0021-8979, eISSN：1089-7550 - A complementary study of the role of the Hall electric field for generation of the force on current-carrying wire in a magnetic field
M. Sakai; N. Honda; F. Fujimoto; O. Nakamura; H. Shibata
American Journal of Physics, Volume：78, Number：2, First page：160, Last page：169, Jan. 2010, [Reviewed], [Lead, Corresponding]
When a current-carrying wire is placed in a transverse magnetic field, a macroscopic force and a transverse Hall electric field are generated. An experimental and theoretical study of the role of the Hall electric field on the generation of the force on the current-carrying wire was conducted employing single-carrier, conventional bipolar type conductors, and unusual bipolar type conductors, in which an approximately zero Hall electric field is expected. It is shown theoretically and experimentally that the collisions of the carrier with the ions solely contribute to the Lorentz force transmission mechanism in the unusual bipolar type conductors, whereas the action of collisions of the carrier with ions as well as the action of the Hall electric field on the lattice ions is responsible for transmission of the Lorentz force in the usual bipolar conductors. A self-consistent treatment of the generation of the Hall electric field is given.
American Association of Physics Teachers (AAPT), Scientific journal
DOI：https://doi.org/10.1119/1.3263818
DOI ID：10.1119/1.3263818, ISSN：0002-9505, eISSN：1943-2909 - Magnetoelectric Effect in Multiferroic CoFe2O4-BaTiO3 Composites
Haruka Tada; Kenji Kamishima; Koichi Kakizaki; Masamichi Sakai; Nobuyuki Hiratsuka
Journal of the Japan Society of Powder and Powder Metallurgy, Volume：57, Number：11, First page：716, Last page：721, 2010, [Reviewed]
Japan Society of Powder and Powder Metallurgy, Scientific journal
DOI：https://doi.org/10.2497/jjspm.57.716
DOI ID：10.2497/jjspm.57.716, ISSN：0532-8799, eISSN：1880-9014 - Dielectric function analysis of superstoichiometric samarium dihydride films
M. Sakai; T. Nanbo; Y. Tanji; O. Nakamura; M. Endo; H. Tajima
Journal of Applied Physics, Volume：105, Number：8, Apr. 2009, [Reviewed], [Lead, Corresponding]
We have carried out an experimental study to reveal the dielectric function of SmHx(x=2.28,2.42,2.56,2.57) films based on room-temperature reflectivity for photon energies ranging from 0.05 to 6.5 eV. The derivation of the dielectric functions has been carried out using model dielectric functions as well as Kramers–Kronig analysis. It is inferred from our analysis that when the H/Sm value is increased from 2.28 to 2.57, (i) the interband transition band located in the ultraviolet region shows a redshift of about 1 eV, (ii) the relatively weak transition band located in the near-infrared region shows a reduction in intensity, and (iii) the unperturbed plasma frequency of free carriers decreases slightly. The behaviors (i), (ii), and (iii) caused by the H/Sm value change are thoroughly approximately the same as those observed for YHx, suggesting that these trends are characteristic of H–M systems showing a metal-insulator transition. It was also confirmed from our structural analysis that these changes in the dielectric function are achieved without a change in the lattice constant. The origin of this constancy in the lattice constant in our samples with different H/Sm values is discussed by assessing the T- and O-site hydrogen concentrations. The hydrogen incorporation effect is also observed in the magnitude of the unperturbed plasma frequency, about 1.7 eV, which is unexpectedly small compared to conventional metals. This characteristic can possibly be attributed to mass enhancement of mobile carriers; we obtained an effective mass of about 10m0 (where m0 is the free electron mass) when the carrier density estimated from the Hall coefficient value is used.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.3088873
DOI ID：10.1063/1.3088873, ISSN：0021-8979, eISSN：1089-7550 - Magnetotransport properties in near-stoichiometric hydride films of YH2+δ under weak fields
M. Sakai; T. Nanbo; O. Nakamura; H. Tajima; Y. Uwatoko
Journal of Applied Physics, Volume：101, Number：10, May 2007, [Reviewed], [Lead, Corresponding]
We have investigated the basic characteristics of mobile carriers in as-deposited thin films of hexagonal-close-packed Y and hydrogenated films of face-centered-cubic YH2+δ. Hall resistance and transverse magnetoresistance measurements were carried out under magnetic fields of up to 1 T at room temperature. The Hall coefficient in YH2+δ showed a minimum value of ∼5×10−12 m3/C when the δ value reached ∼−0.1, in accordance with the δ dependence of resistivity reported previously. Quantitative analysis based on the present measurements revealed that YH2+δ is a compensated metal whose carrier density and mobility were determined to be ∼1.4×1027 (∼1.9×1027) m−3 and ∼3.5×10−3 (∼3.1×10−3) m2 V−1 s−1, respectively, for δ=0.04(−0.03) for both electrons and holes. These carrier parameters were found to account concurrently for the reflection spectral line shapes observed. The compensation observed in YH2+δ is at variance with a simple criterion used previously [E. Fawcett and W. A. Reed, Phys. Rev. 131, 2463 (1963)].
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.2733602
DOI ID：10.1063/1.2733602, ISSN：0021-8979, eISSN：1089-7550 - Photoluminescence characterization of Zn1−xMgxO epitaxial thin films grown on ZnO by radical source molecular beam epitaxy
H. Shibata; H. Tampo; K. Matsubara; A. Yamada; K. Sakurai; S. Ishizuka; S. Niki; M. Sakai
Applied Physics Letters, Volume：90, Number：12, Mar. 2007, [Reviewed], [Last]
The authors report that high-quality Zn1−xMgxO alloys are very brilliant light emitters, even more brilliant than ZnO, particularly in the high-temperature region; both the emission bandwidth and the oscillator strength of the photoluminescence from Zn1−xMgxO alloys increase remarkably with increasing Mg composition ratio x. The authors have revealed that the increase in the oscillator strength is mainly due to the increase in the activation energy required for the nonradiative recombination processes. Therefore, it is suggested that the localization of excitons, because of the compositional fluctuation, takes place in Zn1−xMgxO alloys and that the degree of the localization increases with increasing x.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.2715475
DOI ID：10.1063/1.2715475, ISSN：0003-6951, eISSN：1077-3118 - Specific heat of superstoichiometric samarium dihydride
O. Nakamura; Y. Tanaka; K. Nakazawa; T. Nakano; M. Sakai; S. Orimo; Y. Uwatoko
Journal of Magnetism and Magnetic Materials, Volume：310, Number：2, First page：e65, Last page：e67, Mar. 2007, [Reviewed]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jmmm.2006.10.244
DOI ID：10.1016/j.jmmm.2006.10.244, ISSN：0304-8853 - Galvanomagnetic properties of super and substoichiometric yttrium dihydrides
M. Sakai; T. Nanbo; Y. Tanji; N. Miyazak; O. Nakamura; Y. Uwatoko; H. Tajima
Journal of Magnetism and Magnetic Materials, Volume：310, Number：2, First page：e59, Last page：e61, Mar. 2007, [Reviewed], [Lead, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.jmmm.2006.10.203
DOI ID：10.1016/j.jmmm.2006.10.203, ISSN：0304-8853 - Optical and transport properties of (SmH2) films
O. Nakamura; Y. Tanaka; M. Sakai; T. Nanbo; K. Koyama; Y. Uwatoko; S. Orimo
Physica B: Condensed Matter, Volume：378-380, First page：1138, Last page：1139, May 2006, [Reviewed]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physb.2006.01.456
DOI ID：10.1016/j.physb.2006.01.456, ISSN：0921-4526 - Negative thermal quenching of photoluminescence in ZnO
M. Watanabe; M. Sakai; H. Shibata; C. Satou; S. Satou; T. Shibayama; H. Tampo; A. Yamada; K. Matsubara; K. Sakurai; S. Ishizuka; S. Niki; K. Maeda; I. Niikura
Physica B: Condensed Matter, Volume：376-377, First page：711, Last page：714, Apr. 2006, [Reviewed], [Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physb.2005.12.178
DOI ID：10.1016/j.physb.2005.12.178, ISSN：0921-4526 - A design for electrooptical detection of defect positions in semiconductors
M. Sakai; M. Takeuchi
Physica B: Condensed Matter, Volume：376-377, First page：897, Last page：900, Apr. 2006, [Reviewed], [Lead, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physb.2005.12.224
DOI ID：10.1016/j.physb.2005.12.224, ISSN：0921-4526 - Photoluminescence recombination centers in ZnO
H. Shibata; H. Tampo; M. Sakai; A. Yamada; K. Matsubara; K. Sakurai; S. Ishizuka; K. Kim; P. Fons; K. Iwata; S. Niki; K. Tamura; K. Nakahara; H. Takasu; K. Maeda; I. Niikura
physica status solidi c, Volume：3, Number：4, First page：1026, Last page：1029, Mar. 2006, [Reviewed]
Abstract
We have studied the effects of (i) impurity doping, (ii) rapid thermal annealing, and (iii) crystal polarity control on photoluminescence spectra in the band‐edge emission region of high quality ZnO. As a result, we have discussed the possible lattice defects responsible for some photoluminescence emission peaks, namely (i) peak I 8 appears at 3.3596 eV, (ii) peak I 9 appears at 3.3565 eV and (iii) peak G appears at 3.3327 eV. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley, Scientific journal
DOI：https://doi.org/10.1002/pssc.200564750
DOI ID：10.1002/pssc.200564750, ISSN：1862-6351, eISSN：1610-1642 - Excitation-Power Dependence of Free Exciton Photoluminescence of Semiconductors
Hajime Shibata; Masamichi Sakai; Akimasa Yamada; Koji Matsubara; Keiichiro Sakurai; Hitoshi Tampo; Shogo Ishizuka; Kyoung-Kook Kim; Sigeru Niki
Japanese Journal of Applied Physics, Volume：44, Number：8R, First page：6113, Last page：6113, Aug. 2005, [Reviewed]
We have derived an analytical formula for the excitation-power dependence of the free exciton photoluminescence (PL) intensity. It has been found that the PL intensity I depends on the power of the excitation laser L as I∝L k , where k is the power index. We have deduced the analytical formula that describes the value of k for the free exciton PL emission under the above-band-gap excitation conditions. The results indicate that the value of k is in the region of 1<k<2 depending on both the value of L and material properties such as radiative and competitive nonradiative recombination probabilities.
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1143/jjap.44.6113
DOI ID：10.1143/jjap.44.6113, ISSN：0021-4922, eISSN：1347-4065 - Photoluminescence characterization of excitonic centers in ZnO epitaxial films
M. Watanabe; M. Sakai; H. Shibata; H. Tampo; P. Fons; K. Iwata; A. Yamada; K. Matsubara; K. Sakurai; S. Ishizuka; S. Niki; K. Nakahara; H. Takasu
Applied Physics Letters, Volume：86, Number：22, May 2005, [Reviewed], [Corresponding]
Photoluminescence properties of nominally undoped ZnO thin films grown by radical-source molecular-beam epitaxy have been investigated as a function of (i) sample growth conditions, (ii) excitation laser power density, and (iii) measurement temperatures. Altogether four excitonic emission peaks were observed at photon energy of 3.3646, 3.3606, 3.3572, and 3.3331 eV, which are tentatively denoted as emission peaks A, D, F, and G, respectively. We have classified the defect types responsible for the emission peaks into the following two groups; (i) D and F, whose responsible defect types are suggested to be residual impurities such as aluminum and indium, respectively, and (ii) A and G, whose responsible defect types are suggested to be intrinsic defects such as oxygen vacancies, interstitial zinc, and extended structural defects particularly for G.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.1940730
DOI ID：10.1063/1.1940730, ISSN：0003-6951, eISSN：1077-3118 - 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], [Lead, Corresponding]
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.
AIP Publishing, Scientific journal
DOI：https://doi.org/10.1063/1.1870096
DOI ID：10.1063/1.1870096, ISSN：0021-8979, eISSN：1089-7550 - Characterization of ZnO crystals by photoluminescence spectroscopy
H. Shibata; M. Watanabe; M. Sakai; K. Oka; P. Fons; K. Iwata; A. Yamada; K. Matsubara; K. Sakurai; H. Tampo; K. Nakahara; S. Niki
physica status solidi (c), Volume：1, Number：4, First page：872, Last page：875, Mar. 2004, [Reviewed]
Wiley, Scientific journal
DOI：https://doi.org/10.1002/pssc.200304149
DOI ID：10.1002/pssc.200304149, ISSN：1610-1634 - A nonlocal theory of the Franz–Keldysh effect in semiconductor quantum wires
Masamichi Sakai; Makoto Yamaguchi
Physica E: Low-dimensional Systems and Nanostructures, Volume：21, Number：2-4, First page：367, Last page：371, Mar. 2004, [Reviewed], [Lead, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/j.physe.2003.11.036
DOI ID：10.1016/j.physe.2003.11.036, ISSN：1386-9477 - Electrical Transport and Optical Properties of Hydrogen-Deficient YH
2 Films
Masamichi Sakai; Toru Kontani; Osamu Nakamura; Keishi Takeyama; Yoshiya Uwatoko; Yoshihisa Obi; Koki Takanashi
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, Volume：43, Number：2, First page：681, Last page：687, Feb. 2004, [Reviewed], [Lead, Corresponding]
We have investigated electron transport characteristics of a hydrogen-deficient dihydride of yttrium YH2-3 (-0.3 < & δ < 0.05) focusing particularly on the effect of hydrogen deficiency on carrier relaxation time. At room- and low-temperatures, dc-specific resistivities obtained from electrical measurements show minimum values when hydrogen-deficient quantity δ is approximately -0.1. Optical conductivities were obtained from reflectance measurements by the Kramers-Knonig transformation. When & is changed, the carrier scattering rate determined from the optical conductivity shows a behavior similar to those of dc resistivities. Not only the carrier scattering rate but also a band-gap energy E0 associated with a Γ2-Γ25 transition is influenced by the hydrogen deficiency; E0 shows a maximum value as δ is about -0.1. Hall coefficients are found to be positive but fairly small (∼10-11 m3/C), indicating that electrons as well as holes presumably contribute to electric conduction in YH2+δ.
Scientific journal
DOI：https://doi.org/10.1143/JJAP.43.681
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=2142824286&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=2142824286&origin=inward
DOI ID：10.1143/JJAP.43.681, ISSN：0021-4922, SCOPUS ID：2142824286 - Abrupt Change in Surface Fermi Level of P-Type InP upon Annealing
Tetsuo Kurayama; Gennki Sano; Masamichi Sakai
Japanese Journal of Applied Physics, Volume：41, Number：Part 1, No. 2B, First page：1067, Last page：1071, Feb. 2002, [Reviewed], [Last, Corresponding]
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1143/jjap.41.1067
DOI ID：10.1143/jjap.41.1067, ISSN：0021-4922, eISSN：1347-4065 - NONLOCAL ELECTRO-OPTIC EFFECT IN SEMICONDUCTOR THIN FILMS
MASAMICHI SAKAI
International Journal of Modern Physics B, Volume：15, Number：28n30, First page：3936, Last page：3939, Dec. 2001, [Reviewed], [Lead, Corresponding]
Electroreflectance (ER) spectra of GaAs thin film/ Al 0.3 Ga 0.7 As -substrate systems are investigated theoretically by taking into account the nonlocal effect caused by the presence of a crystal surface. Calculations are carried out by following the previous work by DelSole but considering influence of film thickness and nonflat-band modulation of a static electric field. It is shown from thickness variation of ER spectra that the refractive indexes of the thin films are reduced by a factor of about 0.1 when the nonlocal effect is considered.
World Scientific Pub Co Pte Lt, Scientific journal
DOI：https://doi.org/10.1142/s0217979201009049
DOI ID：10.1142/s0217979201009049, ISSN：0217-9792, eISSN：1793-6578 - Influence of a Surface on the Franz-Keldysh Effect in n- and p-type GaAs Epitaxial Layers
Masamichi Sakai; Hajime Shibata; Masanori Shinohara
Journal of the Physical Society of Japan, Volume：70, Number：4, First page：1064, Last page：1074, Apr. 2001, [Reviewed], [Lead, Corresponding]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.70.1064
DOI ID：10.1143/jpsj.70.1064, ISSN：0031-9015, eISSN：1347-4073 - Pressure Effect of Sr3Fe2O6.80 Studied by Moessbauer Spectroscopy.
H. Kobayashi; M. Kira; H. Onodera; M. Sakai; N. Kuroda; T. Kamimura
THE REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY, Volume：7, First page：670, Last page：672, 1998, [Reviewed]
The Japan Society of High Pressure Science and Technology, Scientific journal
DOI：https://doi.org/10.4131/jshpreview.7.670
DOI ID：10.4131/jshpreview.7.670, ISSN：0917-639X, eISSN：1348-1940 - Photoreflectance study on carrier collisions in near-surface region of n-type GaAs grown by MOCVD
Masamichi Sakai; Masanori Shinohara
Applied Surface Science, Volume：113-114, First page：523, Last page：527, Apr. 1997, [Reviewed], [Lead, Corresponding]
Elsevier BV, Scientific journal
DOI：https://doi.org/10.1016/s0169-4332(96)00838-0
DOI ID：10.1016/s0169-4332(96)00838-0, ISSN：0169-4332 - Influence of Carrier Scattering on Franz-Keldysh Effect in Near-Surface Region ofn-Type GaAs
Masamichi Sakai; Masanori Shinohara
Journal of the Physical Society of Japan, Volume：66, Number：3, First page：738, Last page：748, Mar. 1997, [Reviewed], [Lead, Corresponding]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.66.738
DOI ID：10.1143/jpsj.66.738, ISSN：0031-9015, eISSN：1347-4073 - The effect of pressure on the electronic states of FeS and studied by Mössbauer spectroscopy
Hisao Kobayashi; Masaki Sato; Takashi Kamimura; Masamichi Sakai; Hideya Onodera; Noritaka Kuroda; Yasuo Yamaguchi
Journal of Physics: Condensed Matter, Volume：9, Number：2, First page：515, Last page：527, Jan. 1997, [Reviewed]
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/0953-8984/9/2/019
DOI ID：10.1088/0953-8984/9/2/019, ISSN：0953-8984, eISSN：1361-648X - Optical Investigation of the Magnetic Excitations in Two-Dimensional Triangular Lattice Antiferromagnets
Norimichi KOJIMA; Kōzo Ito; Iwao Mogi; Masayasu Takeda; Giyuu Kido; Yasuaki Nakagawa; Masamichi Sakai; Noritaka Kuroda; Yūichirō Nishina
Journal of the Physical Society of Japan, Volume：62, Number：11, First page：4137, Last page：4145, Nov. 1993, [Reviewed]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.62.4137
DOI ID：10.1143/jpsj.62.4137, ISSN：0031-9015, eISSN：1347-4073 - High-pressure Raman study of vibrational spectra in crystalline acetanilide
Masamichi Sakai; Noritaka Kuroda; Yuichiro Nishina
Physical Review B, Volume：47, Number：1, First page：150, Last page：157, Jan. 1993, [Reviewed], [Lead]
American Physical Society (APS), Scientific journal
DOI：https://doi.org/10.1103/physrevb.47.150
DOI ID：10.1103/physrevb.47.150, ISSN：0163-1829, eISSN：1095-3795 - X-Ray Diffuse Scattering in [Pt(en)2][PtCl2(en)2](ClO4)4
Kazuaki Iwasa; Nobuyoshi Wakabayashi; Masamichi Sakai; Noritaka Kuroda; Yuichiro Nishina
Journal of the Physical Society of Japan, Volume：61, Number：10, First page：3625, Last page：3630, Oct. 1992, [Reviewed]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.61.3625
DOI ID：10.1143/jpsj.61.3625, ISSN：0031-9015, eISSN：1347-4073 - Raman Study of Self-Trapped Phonons in Crystalline Acetanilide Under Hydrdostatic Pressure at Low Temperatures
Masamichi Sakai; Noritaka Kuroda; Yuichiro Nishina
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Volume：216, Number：1, First page：259, Last page：264, Jun. 1992, [Reviewed], [Lead]
Informa UK Limited, Scientific journal
DOI：https://doi.org/10.1080/10587259208028783
DOI ID：10.1080/10587259208028783, ISSN：1058-725X - Optically Induced EPR in Halogen-Bridged Linear Chain Complex [Pt(En)2][Pt(en)2Cl2](Cl04)4, en=NH2CH2CH2NH2
Noritaka Kuroda; Masamichi Sakai; Masashi Suezawa; Yuichiro Nishina; Koji Sumino; Masahiro Yamashita
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Volume：216, Number：1, First page：169, Last page：174, Jun. 1992, [Reviewed]
Informa UK Limited, Scientific journal
DOI：https://doi.org/10.1080/10587259208028768
DOI ID：10.1080/10587259208028768, ISSN：1058-725X - Pressure-induced continuous phase transition of charge-density-wave state in a linear-chain complex
Noritaka Kuroda; Masamichi Sakai; Yuichiro Nishina; Kazuo Sasaki
Physical Review Letters, Volume：68, Number：20, First page：3056, Last page：3059, May 1992, [Reviewed]
American Physical Society (APS), Scientific journal
DOI：https://doi.org/10.1103/physrevlett.68.3056
DOI ID：10.1103/physrevlett.68.3056, ISSN：0031-9007 - ESR Study on Local Structure of UV-Induced Midgap States in [Pt(en)2][Pt(en)2Cl2](ClO4)4, en=ethylenediamine
Masamichi Sakai; Noritaka Kuroda; Masashi Suezawa; Yuichiro Nishina; Koji Sumino; Masahiro Yamashita
Journal of the Physical Society of Japan, Volume：61, Number：4, First page：1326, Last page：1335, Apr. 1992, [Reviewed], [Lead]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.61.1326
DOI ID：10.1143/jpsj.61.1326, ISSN：0031-9015, eISSN：1347-4073 - Raman Scattering by Ethylenediamines in Quasi-One-Dimensional Mixed-Valence Complexes [M(en)2][Pt(en)2Cl2](ClO4)4(M=Pt, Pd, en=ethylenediamine)
Masamichi Sakai; Masayumi Hayakawa; Noritaka Kuroda; Yuichiro Nishina; Masahiro Yamashita
Journal of the Physical Society of Japan, Volume：60, Number：5, First page：1619, Last page：1627, May 1991, [Reviewed], [Lead]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.60.1619
DOI ID：10.1143/jpsj.60.1619, ISSN：0031-9015, eISSN：1347-4073 - ESR Observation of the Motion of Optically Induced Paramagnetic Dimers in [Pt(en)2][Pt(en)2Cl2](ClO4)4(en=ethylenediamine)
Noritaka Kuroda; Masamichi Sakai; Masashi Suezawa; Yuichiro Nishina; Koji Sumino
Journal of the Physical Society of Japan, Volume：59, Number：9, First page：3049, Last page：3052, Sep. 1990, [Reviewed]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.59.3049
DOI ID：10.1143/jpsj.59.3049, ISSN：0031-9015, eISSN：1347-4073 - Optical studies of the quasi-one-dimensional charge-density-wave state in [Pt(en)2][Pt(en)2Cl2](ClO4)4 (en=ethylenediamine) under hydrostatic pressure
Masamichi Sakai; Noritaka Kuroda; Yuichiro Nishina
Physical Review B, Volume：40, Number：5, First page：3066, Last page：3076, Aug. 1989, [Reviewed], [Lead]
American Physical Society (APS), Scientific journal
DOI：https://doi.org/10.1103/physrevb.40.3066
DOI ID：10.1103/physrevb.40.3066, ISSN：0163-1829 - Optical studies of the CDW state in Pt(en)2Cl(ClO4)2under hydrostatic pressures
M Sakai; N Kuroda; Y Nishina
Semiconductor Science and Technology, Volume：4, Number：4, First page：252, Last page：253, Apr. 1989, [Reviewed], [Lead]
IOP Publishing, Scientific journal
DOI：https://doi.org/10.1088/0268-1242/4/4/018
DOI ID：10.1088/0268-1242/4/4/018, ISSN：0268-1242, eISSN：1361-6641 - Soliton-to-Band Optical Absorption in a Quasi One-Dimensional PtII-PtIV Mixed-Valence Complex under Hydrostatic Pressure
N. Kuroda; M. Sakai; Y. Nishina; M. Tanaka; S. Kurita
Physical Review Letters, Volume：58, Number：20, First page：2122, Last page：2125, May 1987
American Physical Society (APS), Scientific journal
DOI：https://doi.org/10.1103/physrevlett.58.2122
DOI ID：10.1103/physrevlett.58.2122, ISSN：0031-9007 - Raman Scattering and X-ray Diffraction Studies on Phase Transitions in ZnCl2under Hydrostatic Pressure
Masamichi Sakai; Noritaka Kuroda; Yuichiro Nishina
Journal of the Physical Society of Japan, Volume：54, Number：11, First page：4081, Last page：4084, Nov. 1985, [Reviewed], [Lead]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.54.4081
DOI ID：10.1143/jpsj.54.4081, ISSN：0031-9015, eISSN：1347-4073 - Anharmonicity of Low Frequency Lattice Vibrations in Red-HgI2
Noritaka Kuroda; Masamichi Sakai; Yuichiro Nishina
Journal of the Physical Society of Japan, Volume：54, Number：4, First page：1423, Last page：1429, Apr. 1985, [Reviewed]
Physical Society of Japan, Scientific journal
DOI：https://doi.org/10.1143/jpsj.54.1423
DOI ID：10.1143/jpsj.54.1423, ISSN：0031-9015, eISSN：1347-4073
- GdxY1-xH2(0≦x≦1)における磁性のGd濃度依存性
桜庭琢士; 酒井政道; 本多善太郎; 工藤駆; 樋口宏二; 北島彰; 大島明博; 長谷川繁彦; 中村修
応用物理学会春季学術講演会講演予稿集(CD-ROM), Volume：62nd, Number：3, First page：ROMBUNNO.11P-A20-6, Last page：32701, 26 Feb. 2015
By simultaneously employing GaAs and Cr4+:YAG saturable absorbers, a diode-pumped doubly passively Q-switched and mode-locked (DP-QML) Nd:Gd3 Ga5 O12 (Nd:GGG)/KTiOPO4 (KTP) green laser has been presented. At the maximum incident pump power of 7.69 W, the obtained average output power, the pulse duration of the Q-switched envelope, the mode-locked pulse width and the pulse repetition rate are 62 mW, 16.8 ns, 352 ps, and 15.5 kHz, respectively, corresponding to a pulse energy of 4.2 µJ and a peak power of 0.25 kW. In comparison with singly passively Q-switched and mode-locked (SP-QML) green laser with GaAs or Cr4+:YAG saturable absorbers, the DP-QML green laser can generate shorter pulse width, deeper modulation depth and higher peak power. The coupled equations for diode-pumped doubly passively QML Nd:GGG/KTP green laser are given and the numerical simulations are in good agreement with the experimental results.
Institute of Physics, Japanese
DOI：https://doi.org/10.7567/JJAP.54.032701
DOI ID：10.7567/JJAP.54.032701, ISSN：0021-4922, J-Global ID：201502244906586733, CiNii Articles ID：150000110164 - 7aPS-111 Anomalous temperature dependence in magnetotransport properties in Gd_xY_<1-x>H_2 (x=0.4)
Sakuraba T.; Kitajima A.; Oshima A.; Hasegawa S.; Nakamura O.; Haruyama S.; Kudo K.; Sakai M.; Honda Z.; Kirigane T.; Numakura R.; Kosaka M.; Higuchi K.
Meeting Abstracts of the Physical Society of Japan, Volume：69, Number：0, First page：257, Last page：257, 2014
The Physical Society of Japan, Japanese
DOI ID：10.11316/jpsgaiyo.69.2.3.0_257_3, ISSN：1342-8349, CiNii Articles ID：110009887121, CiNii Books ID：AA11439205 - Generation of spin current using zero-Hall effect
Sakai Masamichi; Nakamura Osamu; Hasegawa Shigehiko; Kitajima Akira; Oshima Akihiro
Abstract of annual meeting of the Surface Science of Japan, Volume：30, Number：0, First page：385, Last page：385, 04 Nov. 2010
電気の良導体では，キャリヤ散乱レートに関する条件が揃えば、個々の電子および正孔の輸送は残した状態で，ホール係数をゼロにして、印加磁場とバイアス電流に対して垂直な方向への正味の電荷輸送を消失させることが原理的に可能である．講演では，「ホール係数ゼロ状態」を利用する「電流－スピン流変換機能」の原理について説明すると共に，ゼロホール係数物質の探索状況を報告する．
公益社団法人 日本表面科学会, Japanese
DOI：https://doi.org/10.14886/sssj2008.30.0.385.0
DOI ID：10.14886/sssj2008.30.0.385.0, J-Global ID：201102293411541123, CiNii Articles ID：130005038183 - 25aYK-9 Correlation between the Hall Coefficient and Resistivity in YH_x
Sakai M.; Ito M.; Ito S.; Kodama D.; Sakuraba T.; Nakamura O.
Meeting abstracts of the Physical Society of Japan, Volume：64, Number：2, First page：856, Last page：856, 18 Aug. 2009
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110007499137, CiNii Books ID：AA11439205 - 29pRB-12 Temperature dependence of Hall coefficients in YH_x Films (1.7
Sakai M.; Fujita H.; Saito T.; Nakamura O.; Tajima H.
Meeting abstracts of the Physical Society of Japan, Volume：64, Number：1, First page：963, Last page：963, 03 Mar. 2009
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110007373308, CiNii Books ID：AA11439205 - 23pVE-2 Dielectric Function Analysis of YH_x Films (1.7
Sakai M.; Tanji Y.; Endo M.; Nakamura O.; Tajima H.
Meeting abstracts of the Physical Society of Japan, Volume：63, Number：2, First page：894, Last page：894, 25 Aug. 2008
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110006985802, CiNii Books ID：AA11439205 - SmHx(2.2
酒井政道; 丹治義和; 遠藤元気; 中村修; 田島裕之
日本物理学会講演概要集, Volume：63, Number：1, First page：913, 29 Feb. 2008
Japanese
ISSN：1342-8349, J-Global ID：200902251770392017 - YHx薄膜(1.7
酒井政道; 遠藤元気; 中村修
光物性研究会論文集, Volume：19th, First page：282, Last page：285, 2008
Japanese
J-Global ID：200902260954261240 - 金属格子中における水素原子配位ゆらぎと電気伝導機構
酒井政道
Volume：第6号(平成19年度), First page：1, Last page：4, 2008 - 金属格子中における水素原子配位ゆらぎと電気伝導機構
酒井政道
総合研究機構研究プロジェクト研究成果報告書, Volume：第6号(平成19年度), First page：1, Last page：4, 2008 - 20pXB-8 Magneto-Transport Properties in Near-Stoichiometric Dihydride Films
Sakai M.; Tanji Y.; Nakamura O.; Uwatoko Y.; Tajima H.
Meeting abstracts of the Physical Society of Japan, Volume：62, Number：1, First page：975, Last page：975, 28 Feb. 2007
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110007192410, CiNii Books ID：AA11439205 - SmHx薄膜(2.2
丹治義和; 酒井政道; 遠藤元気; 中村修
光物性研究会論文集, Volume：18th, First page：199, Last page：202, 2007
Japanese
J-Global ID：200902287282803231 - 金属格子中の水素配位モフォロジーの多様性にもとづく電子機能
酒井政道
First page：1, Last page：20, 2007 - 遠赤外線領域の光学材料評価技術の開発 ： SmHＸ薄膜（2.2
酒井政道; 遠藤元気; 中村修
Volume：8, First page：32, Last page：35, 2007 - 金属格子中の水素配位モフォロジーの多様性にもとづく電子機能
酒井政道
Volume：第5号(18年度), First page：99, Last page：102, 2007 - 金属格子中の水素配位モフォロジーの多様性にもとづく電子機能
酒井政道
総合研究機構研究プロジェクト成果発表会 : ポスター展示, First page：1, Last page：20, 2007 - 遠赤外線領域の光学材料評価技術の開発 ： SmHＸ薄膜（2.2
酒井政道; 遠藤元気; 中村修
埼玉大学地域共同研究センター紀要, Volume：8, Number：8, First page：32, Last page：35, 2007
We have carried out the dielectric function analysis of SmHｘ(x=2.28, 2.42, 2.56, 2.57) films based on the room-temperature reflectance spectra for photon energies ranging form 0.05 to 6.5 eV. The analysis has been performed by using i) the model dielectric functions and ii) Kramers-Kronig analysis to obtain the real and imaginary parts of the dielectric constants in SmHｘ. The both approaches demonstrate that the interband transition energy shows a red shift of about 1 eV when H/Sm ratio is increased from 2.28 to 2.57, though the lattice constant remains almost unchanged.
Japanese
ISSN：1347-4758, CiNii Articles ID：120001371269, CiNii Books ID：AA11808968 - 遠赤外線領域の光学材料評価技術の開発 ： SmHＸ薄膜（2.2
酒井政道; 遠藤元気; 中村修
埼玉大学地域共同研究センター紀要, Volume：8, First page：32, Last page：35, 2007 - 金属格子中の水素配位モフォロジーの多様性にもとづく電子機能
酒井政道
総合研究機構研究プロジェクト研究成果報告書, Volume：第5号(18年度), First page：99, Last page：102, 2007 - 25pYK-5 A Galvanomagnetic Study on Electron-Hole Compensation in Yttrium Dihydride Films
Sakai M.; Tanji Y.; Nakamura O.; Uwatoko Y.; Tajima H.
Meeting abstracts of the Physical Society of Japan, Volume：61, Number：2, First page：805, Last page：805, 18 Aug. 2006
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110007181963, CiNii Books ID：AA11439205 - 27pTC-4 Speccific Heat and magnetic properies of SmH_<2+δ>
Nakamura O.; Tanaka Y.; Sakai M.; Nakazawa K.; Uwatoko Y.; Orimo S.; Nakano T.
Meeting Abstracts of the Physical Society of Japan, Volume：61, Number：0, First page：552, Last page：552, 2006
The Physical Society of Japan, Japanese
DOI ID：10.11316/jpsgaiyo.61.1.3.0_552_4, ISSN：1342-8349, CiNii Articles ID：110007177834, CiNii Books ID：AA11439205 - 20aYK-1 A Galvanomagnetic Study on Electron-Hole Compensation in Yttrium Dihydride Films
Sakai M.; Nanbo T.; Nakamura O.
Meeting abstracts of the Physical Society of Japan, Volume：60, Number：2, First page：639, Last page：639, 19 Aug. 2005
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110004559382, CiNii Books ID：AA11439205 - イットリウム二水素化物における電子 : 正孔補償状態と磁気抵抗<論文>
酒井政道; 南保岳; 中村修
Volume：1, Number：38, First page：45, Last page：48, 2005
We have investigated compensation characteristics of yttrium dihydride YH2+δ (δ＝−0.03) films by measuring room-temperature galvanomagnetic properties under magnetic field B up to 1 T. The transverse voltages have been measured when a B has x and y components in addition to z component perpendicular to the sample plane. The transverse voltage shows nearly even character with respective to B, while odd characteristic could be expected from simple compensated case where the hole equals the electron only in concentration. The even character observed may be explained by letting the hole equal the electron not only in concentration but also in mobility.
Japanese
ISSN：1880-4446, CiNii Articles ID：120001370722 - 水素と希土類金属を用いた循環型材料開発と電子物性評価
酒井政道
Volume：16年度, First page：179, Last page：182, 2005 - イットリウム二水素化物における電子 : 正孔補償状態と磁気抵抗<論文>
酒井政道; 南保岳; 中村修
埼玉大学紀要, 工学部, 第1部論文集, Volume：1, Number：38, First page：45, Last page：48, 2005
We have investigated compensation characteristics of yttrium dihydride YH2+δ (δ＝−0.03) films by measuring room-temperature galvanomagnetic properties under magnetic field B up to 1 T. The transverse voltages have been measured when a B has x and y components in addition to z component perpendicular to the sample plane. The transverse voltage shows nearly even character with respective to B, while odd characteristic could be expected from simple compensated case where the hole equals the electron only in concentration. The even character observed may be explained by letting the hole equal the electron not only in concentration but also in mobility.
Japanese
ISSN：1880-4446, CiNii Articles ID：120001370722 - 水素と希土類金属を用いた循環型材料開発と電子物性評価
酒井政道
総合研究機構研究プロジェクト研究成果報告書, Volume：16年度, First page：179, Last page：182, 2005 - 水素過剰SmH2+δ薄膜(0.2<δ<0.6)の光学及び輸送特性
南保岳; 折笠強; 酒井政道; 田中幸一; 中村修; 小山和子; 上床美也
Volume：15th, 2004
J-Global ID：200902282859895422 - イットリウム二水素化物におけるキャリヤ補償状態と磁気電気輸送
酒井 政道; 南保 岳; 中村 修
Number：5, First page：85, Last page：89, 2004
We have investigated compensation characteristics of yttriumdihydride YH2+ δfilms by measuring room-temperature galvanomagnetic properties under magnetic field B up to 1 T. The transverse voltages have been measured when a B has x and y components in addition to z component perpendicular to the sample plane (xy-plane). The transverse voltage for YH2+ δ(δ = -0.03) shows nearly even character as a function of B. The even character is probably explained by a nearly compensated case.
Japanese
ISSN：1347-4758, CiNii Articles ID：120001371477, CiNii Books ID：AA11808968 - Optical Properties of Yttrium and Cerium Hydride Films
Kontani T.; Sakai M.; Takeyama K.; Nakamura O.; Koyama K.; Uwatoko Y.
Meeting abstracts of the Physical Society of Japan, Volume：57, Number：2, First page：639, Last page：639, 13 Aug. 2002
The Physical Society of Japan (JPS), Japanese
ISSN：1342-8349, CiNii Articles ID：110009719350, CiNii Books ID：AA11439205
- Relay runner-like spin transport with electron-hole exchange interaction and its application to magnetologic gates
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Pioneering), Jul. 2021 - Mar. 2025
Saitama University
Grant amount(Total)：25870000, Direct funding：19900000, Indirect funding：5970000
Grant number：21K18166 - 細胞分析デバイスよる細胞外シグナルの計測およびその細胞の未来予測
Apr. 2021 - Mar. 2024
Grant amount(Total)：4030000, Direct funding：3100000, Indirect funding：930000
Grant number：21K04194 - 希土類水素化物半導体から構成される薄膜トランジスタとその1Sバンド超伝導
Apr. 2020 - Mar. 2023
Grant amount(Total)：4160000, Direct funding：3200000, Indirect funding：960000
Grant number：20K04583 - Dissipationless spin currents in metallic ambipolar conductors
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Apr. 2019 - Mar. 2023
Saitama University
Grant amount(Total)：17160000, Direct funding：13200000, Indirect funding：3960000
Grant number：19H02413 - Reciprocal accumulation of spins and charges in rare earth hydride bipolar conductors
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Apr. 2015 - Mar. 2018
SAKAI Masamichi; AWANO Hiroyuki; KUROKAWA Yuichiro; KITAJIMA Akira; HIGUCHI Koji; NAKAMURA Osamu; HANAJIRI Tatsuro; NAKAJIMA Yoshikata; TOKUDA Masahide; FUJII Yasuhiko, Saitama University
Grant amount(Total)：4940000, Direct funding：3800000, Indirect funding：1140000
We have proposed a new type of the Hall effect, the signal of which is amplified due to the generation of a sustaining mode of spin current. The conditions indispensable for the observation of the effect are (i) the presence of the transverse component of an effective electric field due to spin splitting in chemical potential in addition to the longitudinal component; (ii) the simultaneous presence of holes and electrons each having approximately the same characteristics; (iii) spin-polarized current injection from magnetized electrodes; (iv) the zero transverse current. The present model was experimentally verified by using van der Pauw-type Hall devices consisting of the nonmagnetic bipolar conductor YH2 and TbFeCo electrodes. Replacing Au electrodes with TbFeCo electrodes alters the Hall resistivity from the ordinary Hall effect to the anomalous Hall-like effect with an enhancement factor of approximately 50 at 4T, cosistent with the present model.
Grant number：15K04648 - A design of spin polarization analyzer and its application to quasi-excusive OR gate
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Challenging Exploratory Research, Apr. 2012 - Mar. 2015
SAKAI Masamichi; HASEGAWA Shigehiko; KITAJIMA Akira; OSHIMA Akihiro, Saitama University
Grant amount(Total)：3900000, Direct funding：3000000, Indirect funding：900000
We have theoretically and experimentally designed the spin-polarization analyzer making use of the quasi-zero Hall coefficient (QZHC) characteristic in bipolar conductors such as dihydride phase of Y and Sc. We derived the closed formulae of Hall resistivity (HR) and transverse magnetoresisitivity (TMR) in the presence of spin splitting in electrochemical potential (ECP) caused by spin-polarized current injection from ferromagnetic electrodes. Our experiments used Co and/or TbFeCo as source and drain electrodes, from which the spin-polarized currents are injected into the bipolar conductor region. As predicted by our calculation, both HR and TMR are enhanced when these magnetic electrodes are used instead of nonmagnetic Au electrode. The enhancement is caused by the coupling mechanism between applied magnetostatic field and spin-orbit interaction through the spin splitting in the ECP. This feature as well as material choice can be applied to operation of exclusive OR gate.
Grant number：24656007 - Generation of Spin Current in Bipolar Conductors with Quasi-Zero Hall Coefficients
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2010 - 2012
SAKAI Masamichi; HONDA Zentaro; HASEGAWA Shigehiko; KITAJIMA Akira; OSHIMA Akihiro, Saitama University
Grant amount(Total)：19890000, Direct funding：15300000, Indirect funding：4590000
The ordinary Hall effect (OHE), which is caused by an external magnetic field, was studied as a mechanism for the generation of spin current. It has been theoretically elucidated that, under an open-circuit condition, the OHE can contribute to spin-current generation when spin-polarized electrons and holes are simultaneously present as mobile carriers. This OHE contribution to spin current generation is caused by the steady-state kinematics of electrons and holes whose transverse velocities have the same direction. The experimental aspects of possible materials for the isomorphic electron and hole systems are argued on the basis of the experimental results of the magnetotransport measurements of the quasi-zero Hall coefficient (QZHC) conductors YH_2 and Gd_xY_<1-x>H_2. For experimental verification of spin current generation, we have investigated the influence of spin injection in these QZHC conductors by employing two type of Hall devices, the current channel region of which are (A) magneticmaterial Gd_xY_<1-x>H_2 (x≒0.4) and (B) nonmagnetic YH_2 but having Co source electrodes and a shortchannel length of approximately 10 μm. Huge anomalous Hall resistivity and positive transversemagnetoresistivity are observed in both Hall devices A and B, showing the generation of spin current.
Grant number：22360003 - Physics and engineering of electronic conduction in hydrogen-metal systems
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2005 - 2008
SAKAI Masamichi, Saitama University
Grant amount(Total)：13750000, Direct funding：13300000, Indirect funding：450000
Grant number：17360005 - 超高圧下における擬一次元分子性結晶中のソリトンに関する分光学的研究
1990 - 1990
Grant amount(Total)：1000000, Direct funding：1000000
Grant number：02750002 - Spectroscopic Study on Dynamical Properties of Solitons in Quasi One-Dimensional Platinum Complexes
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for General Scientific Research (B), 1988 - 1990
KURODA Noritaka; NISHINA Yuichiro; SAKAI Masamichi, Tohoku University
Grant amount(Total)：7300000, Direct funding：7300000
Irradiation of halogen-bridged linear-chain platinum complex by near band-gap light produces mesoscopic defects of valance alternation peculiar to one-dimensional materials with a strong electron-phonon coupling. We have carried out systematic experiments of optical absorption, Raman scattering, and electron paramagnetic resonance in UV irradiated (Pt(en)_2) (Pt(en)_2Cl_2) (C10_4)_4 (en=ethylenediamine) to identify the valence structure of the optically induced defects and to clarify their dynamical properties which have never been studied before.
Detailed analyses of the spectra obtained have led us to conclude that the lowest-entry state of the defect is the spin soliton with S = 1/2. Its valence structure can be regarded as an ideal dimer of Pt ions, and thus its size is as small as about 1 nm. At liquid He temperatures the spin solitons are fluctuating around their equilibrium positinos. At higher temperatres, however, they undergo the translational motin due to hopping along the linear-chain of mixed-valent platinum ions. The activation energy of the hopping motion is as low as 13 meV, so that the correlation rate amounts to 10^9 sec^<-1> at room temperature. They may also diffuse across the chains at elevated temperatures. The life time of the spin soliton is very long, probably longer than several ten hours, as far as the crystal is kept at a certain temperature below 100 K. Nevertheless, the number of spins varies reversibly if the temperature is varied. These observations indicate that the spin solitons are equilibrated thermally with a nonmagnetic state which lies in energy about 14 meV above the spin solitons. On the basis of the one-dimensional Mott-Hubbard model, our spectroscopic information on the electron-phonon coupling energy and the transfer integral suggests that this nonmagnetic state is the charged soliton.
Grant number：63460025 - 擬一次元白金錯体中のソリトンに関する分光学的研究
1987 - 1988
Grant amount(Total)：1500000, Direct funding：1500000
Grant number：62790191 - -
Competitive research funding - -
Competitive research funding