慶應義塾大学 · 物理学・天文学
高橋教授の研究室は、スピンオービタル系におけるスピントロニクス現象とその応用に焦点を当てており、特に金属磁性体/酸化物界面におけるスピン軌道効果や交換バイアスのメカニズムを解明しています。高精度な界面制御とナノ構造の設計を通じて、スピン流の制御とエネルギー効率の向上を実現する材料開発を推進しています。また、レーザー法を用いたナノ材料の成長技術や、EMIシールド、耐摩耗被膜、紫外検出材料への応用も展開しています。
Figures are computed from collected data and may differ slightly.
We report the observation of the intrinsic dampinglike spin-orbit torque (SOT) arising from the Berry curvature in metallic-magnet/CuO_{x} heterostructures. We show that a robust dampinglike SOT, an order of magnitude larger than a fieldlike SOT, is generated in the heterostructure despite the absence of the bulk spin-orbit effect in the CuO_{x} layer. Furthermore, by tuning the interfacial oxidation level, we demonstrate that the fieldlike SOT changes drastically and even switches its sign, whi
Strong electromagnetic wave reflection loss concomitant with second emission pollution limits the wide applications of electromagnetic interference (EMI) shielding textiles. Decoration of textiles by using various dielectric materials has been found efficient for the development of highly efficient EMI shielding textiles, but it is still a challenge to obtain EMI shielding composites with thin thickness. A route of interfacial engineering may offer a twist to overcome these obstacles. Here, we f
We report on the investigation of perpendicular exchange bias in $\mathrm{FePt}(001)/\mathrm{NiO}(\overline{1}\overline{1}1)$ orthogonal exchange couple with FePt partially $\mathrm{L}{1}_{0}$ ordered. From initial magnetization curve measurement and magnetic domain imaging, we find that, for the as-grown bilayer structure, the FePt layer experiences a small-angle magnetization rotation when it is magnetized near to saturation in film normal direction. After field cooling, the bilayer structure
Hard coatings, such as transition metal nitrides, have been widely applied to improve the mechanical properties and tribological performance of cutting tools. The coatings in various multilayered or gradient structures have been designed to meet the demands of more severe service environments and more precise processing requirements. In this work, TiN/TiSiN coatings in several gradient and multilayered structures were deposited on cemented carbides by cathodic arc ion plating using Ti and TiSi a
The oriented growth of β-Ga<sub>2</sub> O<sub>3</sub> films has triggered extensive interest due to the remarkable and complex anisotropy found in the β-Ga<sub>2</sub> O<sub>3</sub> bulks. Remarkable properties, including stronger solar-blind ultraviolet (SBUV) absorption, better mobility, and higher thermal conductivity, are usually observed along <010> direction as compared to other low-index axes. So far, <010>-oriented β-Ga<sub>2</sub> O<sub>3</sub> film growth has been hindered by the lack
Spintronic devices are based on heterojunctions of two materials with different magnetic and electronic properties. Although an energy barrier is naturally formed even at the interface of metallic heterojunctions, its impact on spin transport has been overlooked. Here, using diffusive spin Hall currents, we provide evidence that the inherent energy barrier governs the spin transport even in metallic systems. We find a sizable field-like torque, much larger than the damping-like counterpart, in N
Spin-orbit torque (SOT) induced by the transfer of orbital angular momentum from a lattice to a spin system offers an efficient route for manipulating spin-based devices. Among various potential candidates, three-dimensional topological insulators (TIs) with inherently strong spin-orbit coupling promise to be a powerful source of SOTs. While the huge SOTs observed in ferromagnet (FM)/TI bilayers are generally claimed to be of topological surface states (TSS) nature, the contributions from the su
Defect engineering has been utilized to induce ferromagnetism in various nonmagnetic van der Waals (vdW) crystals, which are vital for fundamental research and applications. Herein, oxygen vacancies were successfully created in montmorillonite, a layered aluminosilicate, by acetic acid treatment and annealing in an argon atmosphere. This treatment facilitated the transition from paramagnetism to room-temperature ferromagnetism with a Curie temperature of 330 K. As the annealing temperature incre
This paper investigates the effect of the addition of nitrogen in FePt layers for ultrathin FePt/AlN multilayer structures. X-ray diffraction results reveal that a compressive stress relaxation occurs after annealing owing to the release of interstitial nitrogen atoms in the FePt layers. The introduction of nitrogen also induces a large in-plane compressive strain during grain growth not seen in FePt deposited without nitrogen. This strain is considered to decrease the driving force for (111) gr
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