Interface-induced field-like optical spin torque in a ferromagnet/heavy metal heterostructure

Ferromagnetic/nonmagnetic heavy metal heterostructures have been widely utilized to efficiently control magnetization via electrical means. Here, we observed in-plane field-like torques induced by a circularly polarized laser pulse in a ferromagnet/nonmagnet heterostructure. The torques significantly increased with decreasing ferromagnetic layer thicknesses. The interfacial field-like optical spin torque was explained by the optical Rashba-Edelstein effect caused by the structural inversion symmetry breaking. This work will aid in the efficient optical manipulation of thin film nanomagnets using optical helicity.