Anisotropic spin relaxation in mesoscopic nonmagnetic channels
Date
2018
Authors
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Publisher
University of Delaware
Abstract
Spin–orbit (SO) effects, which are essential for spintronics, not only generate spin currents and spin torques but also provide ways to modulate spin currents. However, SO effects induce higher rates of spin relaxation and therefore lead to shorter spin-relaxation lengths in materials. This contradicts the general desire for a longer spin-relaxation length to transport a spin current over distance. In this work, we demonstrate that substantial surface spin-orbit effects and a long spin-relaxation length can coexist in mesoscopic Cu channels. ☐ It is a common perception that the transport of a spin current in polycrystalline metal is isotropic and independent of the polarization direction, even though spin current is a tensorlike quantity and its polarization direction is a key variable. We demonstrate surprising anisotropic spin relaxation in mesoscopic polycrystalline Cu channels in nonlocal spin valves. For directions in the substrate plane, the spin-relaxation length is longer for spins parallel to the Cu channel than for spins perpendicular to it, by as much as 9% at 10 K. Spin-orbit effects on the surfaces of Cu channels can account for this anisotropic spin-relaxation. The finding suggests novel tunability of spin current, not only by its polarization direction but also by electrostatic gating.
Description
Keywords
Pure sciences, Applied sciences, Magnetism, Spin current, Spin polarization, Spin relaxation, Spin-orbit coupling, Spintronics