A5036351276- Magnetic properties of thin films
- Heusler alloys: electronic and magnetic properties
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- 2D Materials and Applications
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Graphene research and applications
- Semiconductor materials and interfaces
- Acoustic Wave Resonator Technologies
- Topological Materials and Phenomena
- Advanced Chemical Physics Studies
- Magnetic Properties and Applications
- Advanced Welding Techniques Analysis
- Molecular Junctions and Nanostructures
- Magnetism in coordination complexes
- Inorganic and Organometallic Chemistry
- Surface and Thin Film Phenomena
- Plasmonic and Surface Plasmon Research
- MXene and MAX Phase Materials
- ZnO doping and properties
- Semiconductor materials and devices
- Machine Learning in Materials Science
- Brain Tumor Detection and Classification
National Institute for Materials Science
2019-2025
Mie University
2015-2025
University of Tokyo Hospital
2017
Large interfacial perpendicular magnetocrystalline anisotropy (iPMA) and low Gilbert magnetic damping constant (α) in tunnel junctions (MTJs) are desired to achieve higher storage density lower standby power operations random-access memory. This work theoretically investigates effects of nitrogen fluoride anions (N-anion F-anion) substitution on the MgO barrier interface Fe/MgO/Fe MTJ for iPMA α using first-principles calculations. We find that N-anion significantly enhances by four times...
A density functional theory (DFT)+<italic>U</italic>method based on linear response (LR) was applied to investigate the electronic structures of Co-based full Heusler alloys ternary Co<sub>2</sub>YSi and quaternary Co<sub>2</sub>(Y,Mn)Si.
The first-principles calculation of correlated materials within density functional theory remains challenging, but the inclusion a Hubbard-type effective on-site Coulomb term $({U}_{\mathrm{eff}})$ often provides computationally tractable and physically reasonable approach. However, reported values ${U}_{\mathrm{eff}}$ vary widely, even for same ionic state material. Since final physical results can depend critically on choice parameter computational details, there is need to have consistent...
The spin-1 chiral semimetal is a state of quantum matter hosting unconventional fermions that extend beyond the common Dirac and Weyl fermions. B20-type CoSi prototypal material accommodates such an exotic quasiparticle. To date, spin-transport properties in semimetals have not been thoroughly explored. In this work, we fabricated B20-CoSi thin films on sapphire $c$-plane substrates by magnetron sputtering studied spin Hall effect (SHE) combining experiments first-principles calculations....
Materials informatics has boosted materials design, but the search for optimal atomic configurations in spintronic devices is challenging, due to many degrees of freedom and need design at level. Quantum annealing offers a breakthrough such challenges huge spaces. The authors propose combination quantum annealing, machine learning, first-principles calculations that computationally cheaper than ordinary learning designing atomically disordered spinel oxides (promising magnetoresistive...
Dzyaloshinskii-Moriya interaction (DMI) at metallic multilayer interfaces of Co thin films and heavy-metals X (X=Ir, Pt) was investigated from first principles calculations that treat spin-spirals with the spin-orbit coupling. The results predict sign DMI parameters depends on interfaces, variation orbital moments behaves differently depending parameters.
Half-metallic ferromagnets have been widely investigated by first-principles density-functional theory (DFT) calculations, but extending such studies to investigate spin-polarization at finite temperatures is still challenging due the difficulty of incorporating temperature effects appropriately. We present DFT based on a Green's function formulation, which include thermal via disordered local-moment method address this issue. The calculations are carried out for Heusler...
The ground-state electronic configurations of the correlated organometallic metallocenes, $M{\mathrm{Cp}}_{2},\phantom{\rule{0.28em}{0ex}}M=\mathrm{V}$, Cr, Mn, Fe, Co, and Ni, are investigated using constraint density functional theory combined with nonempirical ${U}_{\mathrm{eff}}$ parameters determined from linear-response theory. relative stability various $d$-orbital these molecules is found to be sensitive amount correlation. Using values ${U}_{\mathrm{eff}}$, calculated in agreement...
Abstract We demonstrated the sensitivity enhancement for magneto-optical surface plasmon resonance (MOSPR) using noble/ferromagnetic metals multilayers. The proposed structure is based on Kretschmann configuration in transverse Kerr effect (TMOKE) methods with FeCu superlattices (SLs) as magneto-plasmonic materials and gelatin biomolecules analyte. dielectric constants of SLs are taken from first principles calculation, which performed by a full-potential linearized augmented plane wave...
Advances in communication technology have moved carrier frequencies to the terahertz (THz) regime where conventional microwave technologies and materials cannot work as their physical properties no longer respond such frequencies. Antiferromagnets are whose magnetic interact with THz-frequency electromagnetic waves. Phenomenologically, response frequency is readily determined by exchange energy anisotropy. In this paper, we revisit antiferromagnetic resonance of NiO, an archetypical...
Electronic configurations and magnetic anisotropy of organometallic metallocenes (MCp2s) were investigated by means first principles calculations based on the constraint density functional theory. The results predict that ground states for M = Cr, Mn, Fe, Co, Ni are E32g,E22g,A11g,E21g, A32g states, respectively. magnetizations CoCp2 NiCp2 energetically favor highly orienting along perpendicular parallel directions to cyclopentadienyl (Cp) plane, respectively, others show almost no...
In materials informatics using machine learning and density functional theory (DFT) calculations, it is often hard to obtain enough database due extremely large costs of DFT. Therefore, required a technique that learns complex target relationship from limited dataset. the present work, overcome this issue, we built neural network by implementing two techniques: Gaussian data augmentation (GDA) method, which injects noises into training dataset, ensemble learning, employs multiple models...
In spintronics, simultaneous realization of high tunneling magnetoresistance and low resistivity in magnetic tunnel junctions (MTJs) is challenging because insulating layers with higher barrier heights generally generate highly spin-polarized currents but increase resistivity. We overcome this trade-off relationship using Brillouin-zone-folded bands at the interfaces Fe/spinel ${\mathrm{MgGa}}_{2}{\mathrm{O}}_{4}/\mathrm{Fe}\phantom{\rule{0.16em}{0ex}}\mathrm{MTJ}$. Interfacial resonant...
The role of magnetic anisotropy on magnon in NiO was theoretically investigated. By using first-principles calculations, parameters spin-exchange constants, magnetocrystalline (MCA) constant, and moment for the by dipole–dipole interaction (MDIA) were extracted, where MDIA is found to have a more dominant contribution than MCA does. Second quantization representation reveals that lifts degeneracy two modes, labeled as α β agrees with experiments. frequency mode has large shift higher due...
We present a structural and density-functional theory study of the interface quasi-twin-free grown three-dimensional topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ on Ge(111). Aberration-corrected scanning transmission electron microscopy energy-loss spectroscopy in combination with first-principles calculations show that weak van der Waals adhesion between quintuple layer Ge can be overcome by forming an additional Te at their interface. The formation energy it to energetically...
Intrinsic spin Hall and anomalous conductivities (SHC AHC) for heterostructures of Co $5d$ heavy metal ($\mathrm{HM}=\mathrm{Ta},\mathrm{W},\mathrm{Re},\mathrm{Os},\mathrm{Ir},\mathrm{Pt}$) are investigated by comparing chemical (HM element) trend different HM thickness means first-principles calculations. We find that the HM-element dependencies SHC AHC caused band filling but importantly originated from characteristic. The associates with Berry curvature in bands inside atomic layers. In...
Experiments on magnetic tunnel junctions (MTJs) show that the use of a (001)-oriented spinel ${\mathrm{Mg}\mathrm{Al}}_{2}{\mathrm{O}}_{4}$ barrier improves robustness tunneling magnetoresistance (TMR) ratio against bias voltage [Sukegawa et al., Appl. Phys. Lett. 96, 212505 (2010)]; however, maximum TMR is very small compared with $\mathrm{Mg}\mathrm{O}$-based MTJ. To overcome this problem, we propose MTJ trilayered tunnel-barrier junction,...