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立野 翔真*; 岡野 元基*; 松尾 衛; 能崎 幸雄*
Physical Review B, 102(10), p.104406_1 - 104406_9, 2020/09
被引用回数：25 パーセンタイル：72.50(Materials Science, Multidisciplinary)In many interacting-electron systems, the microscopic spin angular momentum of electrons is conserved along with the macroscopic angular momentum in electrical current flows, i.e., vorticity. Such spin-vorticity coupling expands the choice of materials for spintronics devices. In this paper, we evaluate the magnitude of an alternating spin current generated by the spin-vorticity coupling with a gigahertz-order surface acoustic wave in a Cu thin film. We measure the gigahertz alternating spin current by an electrical method based on the inverse spin-Hall effect. From the amplitude of the spin current, we can determine the conversion efficiency of the angular momentum between local lattice rotation and electron spin in the Cu film. The conversion efficiency is four orders of magnitude larger than the case of spin current generation via kilohertz-order vorticity in turbulent flow of liquid mercury.
岡野 元基*; 松尾 衛; 大沼 悠一*; 前川 禎通*; 能崎 幸雄*
Physical Review Letters, 122(21), p.217701_1 - 217701_6, 2019/05
被引用回数：92 パーセンタイル：95.08(Physics, Multidisciplinary)We experimentally demonstrate the nonreciprocal generation of spin current (
) in a surface-oxidized copper film. The efficiency of conversion is at least 320 times larger than the inverse conversion. This nonreciprocity is due to a novel type of generation, which relies on the transfer of angular momentum from the velocity field of free electrons. A gradient in the electrical mobility in the film produces vorticity in the in-plane drift velocity of the free electrons. The inverse process can hardly occur when is collinear with the gradient in the electrical mobility.
