Optical spin-orbit torque in heavy metal-ferromagnet heterostructures.

Choi, Gyung-Min; Oh, Jung Hyun; Lee, Dong-Kyu; Lee, Seo-Won; Kim, Kun Woo; Lim, Mijin; Min, Byoung-Chul; Lee, Kyung-Jin et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Spin current generation through the spin-orbit interaction in non-magnetic materials lies at the heart of spintronics. When the generated spin current is injected to a ferromagnet, it produces spin-orbit torque and manipulates magnetization efficiently. Optically generated spin currents are expected to be superior to their electrical counterparts in terms of the manipulation speed. Here we report optical spin-orbit torques in heavy metal/ferromagnet heterostructures. The strong spin-orbit coupling of heavy metals induces photo-excited carriers to be spin-polarized, and their transport from heavy metals to ferromagnets induces a torque on magnetization. Our results demonstrate that heavy metals can generate spin-orbit torque not only electrically but also optically.