Optical spin-orbit torque in heavy metal-ferromagnet heterostructures
Gyung‐Min Choi, Jung Hyun Oh, Dong Kyu Lee, Seo-Won Lee, Kun Woo Kim, Mijin Lim, Byoung‐Chul Min, Kyung‐Jin Lee, Hyun‐Woo Lee
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.