Fig. 1: Schematics for mechanism.
From: Optical spin-orbit torque in heavy metal-ferromagnet heterostructures
A right circularly polarized light (σ+) generates a spin-polarized electron (filled circle) and hole (empty circle) excitations in HM (Blue arrows indicate the spin angular momentum). A spin transport from HM to FM induces a damping-like torque on the magnetization of FM (green arrow). A light propagates to the z-direction, and initial magnetization lies along the x-direction.
