A5034910678- Heusler alloys: electronic and magnetic properties
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Physics of Superconductivity and Magnetism
- Sexual function and dysfunction studies
- MXene and MAX Phase Materials
- Sperm and Testicular Function
- Hormonal and reproductive studies
- Magnetic Properties and Applications
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Sexuality, Behavior, and Technology
- Sexual Differentiation and Disorders
- Iron-based superconductors research
- Inorganic Chemistry and Materials
- 2D Materials and Applications
- Rare-earth and actinide compounds
- Chalcogenide Semiconductor Thin Films
- High-pressure geophysics and materials
- Advanced Chemical Physics Studies
- Surface and Thin Film Phenomena
- Urinary Bladder and Prostate Research
- Quantum and electron transport phenomena
- Neuroscience of respiration and sleep
Tohoku University
2015-2024
Spintronics Research Network of Japan
2014-2024
Osaka University
1994-2022
Physical Devices (United States)
2003-2020
Hitachi (Japan)
1995-2018
Advanced Institute of Materials Science
2018
Canadian Nautical Research Society
2018
National Cerebral and Cardiovascular Center
1995-2017
SPring-8
2014-2016
National Institute for Materials Science
2014-2016
We investigate the atomic disorder effects on half-metallicity of full-Heusler alloy ${\mathrm{Co}}_{2}({\mathrm{Cr}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x})\mathrm{Al}$ from first principles by using Korringa-Kohn-Rostoker method with coherent potential approximation. Our results show that between Cr and Al does not significantly reduce spin polarization parent ${\mathrm{Co}}_{2}\mathrm{CrAl},$ while Co makes a considerable reduction polarization. It is observed decreases increasing Fe...
A new class of half-metallic ferromagnets has been found in the zinc-blende crystal structure. The previously nonexistent CrAs thin films have synthesized on GaAs (001) substrates by molecular-beam epitaxy, and show a ferromagnetic behavior at room temperature. designed ab initio calculations based local spin-density approximation, calculation predicts highly spin-polarized electronic band
Gilbert damping for the epitaxial Co2FeAl Heusler alloy films was investigated. constant evaluated by analyzing data of ferromagnetic resonance measured at frequency 2–20 GHz. film without annealing rather large, while it decreased remarkably with postannealing. annealed 600 °C ≃0.001. These behavior can be well explained fact that density states calculated from first principles decreases increasing degree B2 order.
Fully epitaxial current-perpendicular-to-plane giant magnetoresistance (MR) devices with half-metallic ${\text{Co}}_{2}\text{MnSi}$ (CMS) electrodes and a Ag spacer were fabricated to investigate the relationship between chemical ordering in CMS its MR properties, including bulk interface spin-asymmetry coefficients $\ensuremath{\beta}$ $\ensuremath{\gamma}$. CMS/Ag/CMS annealed at $550\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ shows largest ratio: 36.4% 67.2% RT 110 K,...
Fully epitaxial Co2FexMn1−xSi(CFMS)/Ag/Co2FexMn1−xSi current-perpendicular-to-plane giant magnetoresistive devices with various Fe/Mn ratios x and top CFMS layer thicknesses tCFMS were prepared. The highest magnetoresistance (MR) ratios, 58% at room temperature 184% 30 K, observed in the sample = 0.4 3 nm. Enhancement of interface spin-asymmetry was suggested for compared that 0. A MR ratio also even a very thin trilayer structure, CFMS(4 nm)/Ag(3 nm)/CFMS(2 nm), which is promising...
Abstract Electric fields at interfaces exhibit useful phenomena, such as switching functions in transistors, through electron accumulations and/or electric dipole inductions. We find one potentially unique situation a metal–dielectric interface which the field is atomically inhomogeneous because of strong electrostatic screening effect metals. Such enable us to access quadrupoles shell. Here we show, by synchrotron X-ray absorption spectroscopy, induction magnetic moments platinum monatomic...
We investigated the origin of perpendicular magneto-crystalline anisotropy (MCA) in L10 ordered FeNi alloy using first-principles density-functional calculations. found that MCA L10-FeNi arises predominantly from constituent Fe atoms, which is consistent with recent measurements orbital magnetic moment by x-ray circular dichroism. Analysis second-order perturbation spin-orbit interaction indicates spin-flip excitations between occupied majority-spin and unoccupied minority-spin bands make a...
Voltage control of spin enables both a zero standby power and ultralow active consumption in spintronic devices, such as magnetoresistive random-access memory devices. A practical approach to achieve voltage is the electrical modulation spin–orbit interaction at interface between 3d-transition-ferromagnetic-metal dielectric layers magnetic tunnel junction (MTJ). However, we need initiate new guideline for materials design improve voltage-controlled anisotropy (VCMA) perpendicular (PMA). Here...
We administered intracavernous injections of 20 micrograms. prostaglandin E1 to 135 patients with impotence, and evaluated the effects side effects. Among who underwent injection complete erection was observed in 83 (62 per cent), while incomplete noted 33 (24 cent). In both groups sufficient for sexual intercourse. Tumescence without rigidity 12 no response obtained 7. Poor seen frequently disorders vascular system and/or damage cavernous body penis. Priapism after not observed. Moreover,...
Magnetization measurements have been carried out at high pressure up to 12.1 kbar for ${\text{Co}}_{2}\text{VAl}$ and ${\text{Co}}_{2}\text{VGa}$ with a miniature high-pressure clamp cell. The magnetic moment measured 5 K is independent of ${\text{Co}}_{2}\text{VGa}$. This an experimental observation that gives clear evidence possesses half-metallic electronic structure. On the other hand, sizable dependence observed it attributed precipitation bcc particles in matrix $L{2}_{1}$ phase. Curie...
We report enhanced tunnel magnetoresistance (TMR) ratios of 188$%$ (308$%$) at room temperature and 328$%$ (479$%$) 15 K for cation-site-disordered MgAl${}_{2}$O${}_{4}$-barrier magnetic junctions (MTJs) with Fe (Fe${}_{0.5}$Co${}_{0.5}$ alloy) electrodes, which exceed the TMR theoretically calculated experimentally observed ordered spinel barriers. The enhancement is attributed to suppression so-called band-folding effect in MTJs [Phys. Rev. B 86, 024426 (2012)]. First-principles...
Tunnel magnetoresistance (TMR) in MgO-based magnetic tunnel junctions (MTJs) with equiatomic quaternary CoFeMnSi Heusler and CoFe alloy electrodes is studied. The epitaxial MTJ stacking structures were prepared using ultrahigh-vacuum magnetron sputtering, where the electrode has a full B2 partial L21 ordering crystal structure. Maximum TMR ratios of 101% 521% observed at room temperature 10 K, respectively, for MTJs. large bias voltage dependence ratio was also low (LT), as similarly Co2MnSi...
We investigated the voltage-controlled magnetic anisotropy (VCMA) in an ultrathin Ir-doped Fe layer with a CoxFe1−x termination layer. The VCMA effect depends on concentration of alloy, and large coefficient, as high −350 fJ/Vm, was obtained Co-rich First principles calculations revealed that increased is due not only to added Co atoms but also Ir adjacent atoms. Interface engineering using CoFe effective for recovering tunneling magnetoresistance while maintaining effect. developed...
We perform the first-principles density functional calculations of Co-based full-Heusler alloys, exploring 25 possible combinations Co2YZ (Y=Ti, V, Cr, Mn, and Fe; Z=Al, Ga, Si, Ge, Sn) in order to clarify stability for Co-related atomic disorder, because this type disorder is considered degrade spin polarization Co2YZ. found that between Co Y atoms correlates with total valence electron charges around atom, a difference leads different shape local potential at each site. This means Ti-based...
Using an X-ray TV system, we analyzed responses in the internal diameter (ID), flow velocity, and volume small pulmonary vessels (100–600 microns ID) during unilobar hypoxia hypercapnia cats. In hypoxic hypercapnic lobes, ID reduced proportion to degree of hypercapnia, respectively. The reduction was larger arteries than veins for a given stimulus. arteries, nonuniformly series-arranged response both stimuli. percentage maximal 200–300 ID, which it 21, 26, 28, 36% with 5% O2, 0% CO2, 10% CO2...
The electron-lattice interaction of BaPb1-xBixO3 (BPB) and BaxK1-xBiO3 (BKB) is studied microscopically by using the realistic electronic bands BaBiO3 reproduced tight-binding model. It found that coupling coefficients have strong wavevector mode dependences. causes a remarkable renormalization longitudinal oxygen stretching and/or breathing vibration. Superconductivity discussed in framework strong-coupling theory phonon mechanism. spectral function alpha 2F( omega ) has some prominent...
We present first-principles based calculations of electronic structures and tunneling conductance ${\text{Co}}_{2}YZ/\text{MgO}(\ensuremath{\sim}2\text{ }\text{nm})/{\text{Co}}_{2}YZ(001)$ $(YZ=\text{MnSi},\text{CrAl})$ magnetic tunnel junctions (MTJs). It is found that $YZ$(MnSi CrAl)-terminated interfaces are thermodynamically stable as compared with Co-terminated in ${\text{Co}}_{2}YZ/\text{MgO}(001)$ junctions. In the CrAl-termination, no interface states appear both sides junctions,...
We investigated the spin-dependent transport properties of Fe/MgAl2O4/Fe(001) magnetic tunneling junctions (MTJs) on basis first-principles calculations electronic structures and ballistic conductance. The calculated magnetoresistance (TMR) ratio a MTJ was about 160%, which much smaller than that Fe/MgO/Fe(001) (1600%) for same barrier thickness. However, there an evanescent state with delta 1 symmetry in energy gap around Fermi level normal spinel MgAl2O4, indicating possibility large TMR...
In this study, the microscopic origins of voltage-controlled magnetic anisotropy (VCMA) in 3d-ferromagnetic metals are revealed. Using in-situ X-ray fluorescence spectroscopy that provides a high quantum efficiency, electric-field-induced changes orbital moment and dipole Tz terms ultrathin Co films demonstrated. An difference 0.013{\mu}B. was generated presence electric fields +(-)0.2 V/nm. The VCMA properly estimated by induced change moment, according to perturbation theory model. term...