Kazuya Ando 교수

Using the spin Hall effect, magnetization relaxation in a Ni_{81}Fe_{19}/Pt film is manipulated electrically. An electric current applied to the Pt layer exerts spin torque on the entire magnetization of the Ni81Fe19 layer via the macroscopic spin transfer induced by the spin Hall effect and modulates the magnetization relaxation in the Ni81Fe19 layer. This method allows us to tune the magnetization dynamics regardless of the film size without applying electric currents directly to the magnetic

The inverse spin-Hall effect (ISHE) induced by the spin pumping has been investigated systematically in simple ferromagnetic/paramagnetic bilayer systems. The spin pumping driven by ferromagnetic resonance injects a spin current into the paramagnetic layer, which gives rise to an electromotive force transverse to the spin current using the ISHE in the paramagnetic layer. In a Ni81Fe19/Pt film, we found an electromotive force perpendicular to the applied magnetic field at the ferromagnetic resona

The spin-orbit interaction in a solid couples the spin of an electron to its momentum. This coupling gives rise to mutual conversion between spin and charge currents: the direct and inverse spin Hall effects. The spin Hall effects have been observed in metals and semiconductors. However, the spin/charge conversion has not been realized in one of the most fundamental semiconductors, silicon, where accessing the spin Hall effects has been believed to be difficult because of its very weak spin-orbi

The spin Hall effect is a spin-orbit coupling phenomenon, which enables electric generation and detection of spin currents. This relativistic effect provides a way for realizing efficient spintronic devices based on electric manipulation of magnetization through spin torque. However, it has been believed that heavy metals are indispensable for the spin-torque generation. Here we show that the spin Hall effect in Cu, a light metal with weak spin-orbit coupling, is significantly enhanced through n

The polar-angular dependence of the magnetization in electromotive force induced by the spin pumping has been investigated for a ${\text{Ni}}_{81}{\text{Fe}}_{19}/\text{Pt}$ film to examine the model of the inverse spin-Hall effect (ISHE). In the experiment, the magnetization-direction dependence of the electromotive force is estimated directly by the simultaneous measurement of the ferromagnetic resonance field and the electromotive force signal. The experimental results are well reproduced by

ABSTRACT Alumina/silicon carbide (Al 2 O 3 /SiC) composite ceramics with large self‐crack‐healing ability, high strength and high heat‐resistance limit temperature for strength were developed and subjected to three‐point bending. A semicircular surface crack 100 μm in diameter was made on each sample. Crack‐healing behaviour was systematically studied, as functions of crack‐healing temperature and healing time, and the fatigue strengths of the crack‐healed sample at room temperature and 1373 K w

Ceramic (Si3 N4 /SiC) composites have been produced by sintering. From the sintered block, three point bend specimens were cut out. A semi‐circular crack was made on the centre of the tension surface of the test specimen with the aid of a Vicker’s indenter. The diameter of the semi‐circular crack was about 60–70 μm. The specimens were subsequently heat treated at 1300°C for 1 h in vacuum, nitrogen or air. The bending strength was measured at room temperature, 800 and 1000°C. The specimens heat t

The generation efficiency of spin currents induced by a magnetization-precession motion in a thin film system has been investigated in terms of a magnetization-precession trajectory. By using the Landau–Lifshitz–Gilbert equation combined with the phenomenological model of the spin pumping, the generation efficiency is calculated to be equal to the elliptical orbit area of magnetization precession, which is maximized when the precession trajectory is distorted. This calculation well reproduces ex

The photoinduced inverse spin-Hall effect was observed in a Pt/GaAs hybrid structure. In the GaAs layer, circularly polarized light generates spin-polarized carriers, inducing a pure spin current into the Pt layer through the interface. This pure spin current is, by the inverse spin-Hall effect in the Pt layer, converted into electric voltage. By changing the direction and ellipticity of the circularly polarized light, the electromotive force varies systematically, consistent with the prediction

Spin wave resonance in Ni81Fe19/Pt thin wire arrays has been investigated using the inverse spin-Hall effect (ISHE). The spin wave in the Ni81Fe19 layer drives spin pumping, generation of spin currents from magnetization precession, and the pumped spin current is converted into a charge current by ISHE in the Pt layer. We found an electromotive force transverse to the spatial and the spin-polarization directions of the spin current. The experimental results indicate that the amplitude of the ele

Current-induced spin-orbit torques provide an effective way to manipulate magnetization in spintronic devices, promising for fast switching applications in nonvolatile memory and logic units. Recent studies have revealed that the spin-orbit torque is strongly altered by the oxidation of heterostructures with broken inversion symmetry. Although this finding opens a new field of metal-oxide spin-orbitronics, the role of the oxidation in the spin-orbit physics is still unclear. Here, we demonstrate