A5084775651- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Magnetic properties of thin films
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- Rare-earth and actinide compounds
- Surface and Thin Film Phenomena
- Magnetic Properties and Applications
- Electronic and Structural Properties of Oxides
- Iron-based superconductors research
- High-pressure geophysics and materials
- ZnO doping and properties
- Quantum, superfluid, helium dynamics
- Magneto-Optical Properties and Applications
- Magnetic Properties of Alloys
- Characterization and Applications of Magnetic Nanoparticles
- Multiferroics and related materials
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Organic and Molecular Conductors Research
- Advanced Chemical Physics Studies
- Superconducting Materials and Applications
- Topological Materials and Phenomena
- Advanced Memory and Neural Computing
Japan Atomic Energy Agency
2016-2025
RIKEN Center for Emergent Matter Science
2018-2025
Kavli Institute for Theoretical Sciences
2018-2025
University of Chinese Academy of Sciences
2018-2025
RIKEN
2025
University of Yamanashi
2005-2025
Advanced Science Research Center
2015-2024
Tohoku University
2002-2023
The University of Tokyo
1986-2023
Advanced Institute of Materials Science
2006-2023
Reversible spin Hall effect comprising the direct and inverse effects was electrically detected at room temperature. A platinum wire with a strong spin-orbit interaction is used not only as current absorber but also spin-current source in specially designed lateral structure. The obtained conductivities are 2.4 x 10(4) (Omega m)(-1) temperature, times larger than previously reported values of semiconductor systems. Spin from both experimentally confirmed to be same, demonstrating Onsager...
We study theoretically the thermopower in cobalt oxides generalizing Heikes formula. In oxides, states of carriers are largely degenerate because crystalline field and Hund's rule coupling compete ions. It is shown that degeneracy, together with strong correlation $3d$ electrons, causes large thermopower. The recent experiments ${\mathrm{NaCo}}_{2}{\mathrm{O}}_{4}$ discussed light theoretical result.
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Ken-ichi Uchida, Hiroto Adachi, Takeru Ota, Hiroyasu Nakayama, Sadamichi Maekawa, Eiji Saitoh; Observation of longitudinal spin-Seebeck effect in magnetic insulators. Appl. Phys. Lett. 25 October 2010; 97 (17): 172505. https://doi.org/10.1063/1.3507386 Download citation file: Ris (Zotero) Reference Manager...
Using the spin Hall effect, magnetization relaxation in a Ni_{81}Fe_{19}/Pt film is manipulated electrically. An electric current applied to Pt layer exerts torque on entire of Ni81Fe19 via macroscopic transfer induced by effect and modulates layer. This method allows us tune dynamics regardless size without applying currents directly magnetic
The spin Seebeck effect is a spin-motive force generated by temperature gradient in ferromagnet that can be detected via normal metal contacts through the inverse Hall [K. Uchida {\it et al.}, Nature {\bf 455}, 778-781 (2008)]. We explain this pumping at contact proportional to spin-mixing conductance of interface, temperature-dependent magnetic coherence volume, and difference between magnon electron [D. J. Sanders D. Walton, Phys. Rev. B 15}, 1489 (1977)].
The inverse spin-Hall effect (ISHE) induced by the spin pumping has been investigated systematically in simple ferromagnetic/paramagnetic bilayer systems. driven ferromagnetic resonance injects a current into paramagnetic layer, which gives rise to an electromotive force transverse using ISHE layer. In Ni81Fe19/Pt film, we found perpendicular applied magnetic field at condition. spectral shape of is well reproduced Lorentz function, indicating that due pumping; extrinsic magnetogalvanic...
We study theoretically the spin transport in a nonmagnetic metal connected to ferromagnetic injector and detector electrodes. derive general expression for accumulation signal which covers from metallic tunneling regime. This enables us discuss recent controversy on injection detection experiments. Extending result superconducting device, we find that is strongly enhanced by opening of gap since gapped superconductor low carrier system but not charge. The enhancement also expected...
A mechanism for the large magnetoresistance observed recently in Co-Al-O granular magnetic films is presented. It shown that resistivity decreases with increasing applied field because spin-dependent tunneling increases as relative orientation of magnetization between grains becomes parallel. With this we are able to account dependence on and temperature.
Spin-polarized tunneling of electrons through Ni-NiO-Ni, Co, and Fe junctions is discussed. The hysteresis the resistance in a magnetic field originates magnetization process demonstrates new interplay electronic properties ferromagnetic metals.
Angle-resolved photoemission data from one-dimensional SrCu${\mathrm{O}}_{2}$ compounds are found to be qualitatively different that of two-dimensional S${\mathrm{r}}_{2}$Cu${\mathrm{O}}_{2}$C${\mathrm{l}}_{2}$. The can quantitatively accounted for by the exact diagonalization calculation based on t-J model. We identify two underlying bands having approximately 1.2 and 0.3 eV energy dispersion as holon spinon, with their scaled t J, respectively.
Electronic-energy-level structures of the layered Cu oxide compounds are drawn within ionic model. Correlations between level separations obtained and superconducting critical temperature ${\mathit{T}}_{\mathit{c}}$ examined for all families superconductors. It is proposed that position energy apex oxygen atoms primary importance electronic states ${\mathrm{CuO}}_{2}$ plane governs optimum ${\mathit{T}}_{\mathit{c}}$'s hole-carrier suprconductors. The pressure effect discussed this...
The spin Seebeck effect refers to the generation of a voltage caused by temperature gradient in ferromagnet, which enables thermal injection currents from ferromagnet into an attached nonmagnetic metal over macroscopic scale several millimeters. inverse Hall converts injected current transverse charge voltage, thereby producing electromotive force as conventional device. Recent theoretical and experimental efforts have shown that magnon phonon degrees freedom play crucial roles effect. In...
Effects of Zeeman splitting and spin-orbit scattering on the resistance in two-dimensional disordered systems are theoretically studied. The field dependence magnetoresistance is shown to have characteristic anisotropy. present theory explains qualitative features experimental observations by Komori et al. Cu granular films.
We formulate a linear response theory of the spin Seebeck effect, i.e., voltage generation from heat current flowing in ferromagnet. Our approach focuses on collective magnetic excitation spins, magnons. show that linear-response formulation provides us with qualitative as well quantitative understanding effect observed prototypical magnet, yttrium iron garnet.
Abstract Magnons are the elementary excitations of a magnetically ordered system. In ferromagnets, only single band low-energy magnons needs to be considered, but in ferrimagnets situation is more complex owing different magnetic sublattices involved. this case, low lying optical modes exist that can affect dynamical response. Here we show spin Seebeck effect (SSE) sensitive complexities magnon spectrum. The SSE caused by thermally excited dynamics converted voltage inverse Hall at interface...
Here, we report the observation of strong coupling between magnons and surface acoustic wave (SAW) phonons in a thin CoFeB film constructed an on-chip SAW resonator by analyzing phonon dispersion anticrossings. We employ nanostructured design that, contrast to conventional resonators, allows us enhance shear-horizontal strain. Crucially, this type strain couples strongly magnons. Our device provides tunability thickness with fixed wavelength, which is departure from approach magnon-phonon...
We study the temperature and bias-voltage dependence of magnetoresistance (MR) in insulating Co-Al-O granular films. The MR exhibits strong is enhanced more than 20% at low temperatures, while it has no appreciable change dependence. results provide clear evidence for successive onset higher-order processes spin-dependent tunneling between large granules through intervening small ones with Coulomb blockade. remarkable contrast consistently explained.
We study the Kondo effect in a quantum dot coupled to ferromagnetic leads and analyze its properties as function of spin polarization leads. Based on scaling approach, we predict that for parallel alignment magnetizations strong-coupling limit is reached at finite value magnetic field. Using an equation motion technique, nonlinear transport through dot. For alignment, zero-bias anomaly may be split even absence external antiparallel symmetric coupling, peak only presence field, but shows...
We study spin-dependent electron tunneling in ferromagnetic junctions containing small metallic islands. The matrix elements depend on the relative direction of magnetization island and electrodes. dependence amplifies cotunneling Coulomb blockade regime. show that single-electron transistors magnetoresistance is strongly enhanced by blockade. results provide a theoretical basis for recent experiments transistors, double tunnel junctions, granular materials.