[21p-W241-1~21] 10.2 Spin torque, spin current, circuits, and measurement technologies

▲ [21p-W241-10] Conversion of spin current into charge current in Bi_0.85Sb_0.15

〇Ryohei Kumamoto¹, Yuichiro Ando¹, Sergey Dushenko^1,2, Teruya Shinjo¹, Masashi Shiraishi¹ (1.Kyoto Univ., 2.Osaka Univ.)

Keywords:Inverse spin Hall effect,Bismuth

In spintronics, materials with a large spin Hall angle are desired, since effective conversion between charge current and pure spin current is important for realization of novel spintronics devices. Bi and Bi-based alloys are expected to have a large spin Hall angle because of the large spin-orbit couplings of Bi atoms and the Dirac electrons located at the L-point band. In theory, the spin Hall resistivity is proportional to the orbital susceptibility in the Dirac electron system, and it is estimated to be 100 times larger in Bi and BiSb than in Pt, which allows efficient spin conversion. Thus, we expected significant enhancement of a spin Hall angle in Bi_0.85Sb_0.15 because of its carriers located at the L-point and semiconducting properties.
In this study, Bi_0.85Sb_0.15 was deposited on top of a ferrimagnet, Y₃Fe₅O₁₂ or YIG. Spin current was injected into the Bi_0.85Sb_0.15 from the YIG under the ferromagnetic resonance conditions, by irradiating microwave with a frequency 9.12 GHz and sweeping external magnetic field which is directed parallel to the sample. The injected spin current was expected to be converted into charge current due to the inverse spin Hall effect in the Bi_0.85Sb_0.15. Electromotive force from the Bi_0.85Sb_0.15 was detected under the ferromagnetic resonance conditions. Sign inversion of the electromotive force with the reversal of the magnetic field and a proportional relationship between electromotive force and microwave power were observed. These results suggest that the electromotive force in the Bi_0.85Sb_0.15 was induced by the inverse spin Hall effect.