Keio University · 물리·천문학
Tenghua Gao 교수의 연구실은 스핀트로닉스 및 나노구조 헤테로구조에서의 스핀 운반과 자기적 상호작용을 중심으로 연구를 진행하고 있습니다. 특히, 스핀오르빗 토크, 표면 및 계면에서의 전자적 비대칭성, 그리고 나노구조계면에서의 전자기적 특성 제어에 초점을 맞추고 있으며, 고성능 전자소자 및 EMI 차폐 소재 개발에도 기여하고 있습니다. 다양한 물질 조합(예: FePt/NiO, NiFe/BiSb, SiC/나노입자 등)을 활용한 이종접합 시스템의 기초 물리적 메커니즘 규명이 핵심입니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
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