Optical spin transfer and spin-orbit torques in thin film ferromagnets

Abstract

We study the optically induced torques in thin film ferromagnetic layers under excitation by circularly polarized light. We study cases both with and without Rashba spin-orbit coupling using a 4-band model. In the absence of Rashba spin-orbit coupling, we derive an analytic expression for the optical torques, revealing the conditions under which the torque is mostly derived from optical spin transfer torque (i.e. when the torque is along the direction of optical angular momentum), versus when the torque is derived from the inverse Faraday effect (i.e. when the torque is perpendicular to the optical angular momentum). We find the optical spin transfer torque dominates provided that the excitation energy is far away from band edge transitions, and the magnetic exchange splitting is much greater than the lifetime broadening. For the case with large Rashba spin-orbit coupling and out-of-plane magnetization, we find the torque is generally perpendicular to the photon angular momentum and is ascribed to an optical Edelstein effect.

10 pages, 5 figures

References in corpus (12)

• Spin Transfer Torques
• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• All-optical control of ferromagnetic thin films and nanostructures
• Giant Rashba Splitting in CH3NH3PbBr3 Organic-Inorganic Perovskite
• Ab Initio Theory of Coherent Laser-Induced Magnetization in Metals
• Photo-induced precession of magnetization in ferromagnetic (Ga,Mn)As
• Single shot ultrafast all optical magnetization switching of ferromagnetic Co/Pt multilayers
• Laser-induced torques in metallic ferromagnets
• Current Induced Order Parameter Dynamics: Microscopic Theory Applied to Co/Cu/Co spin valves
• Spin-Orbit Torques in Two-Dimensional Rashba Ferromagnets
• Femtosecond Coherent Control of Spin with Light in (Ga,Mn)As ferromagnets
• Theory of light-induced effective magnetic field in Rashba ferromagnets

Cited by in corpus (7)

• TMOKE as efficient tool for the magneto-optic analysis of ultra-thin magnetic films
• Rectification of Spin Current in Inversion-Asymmetric Magnets with Linearly-Polarized Electromagnetic Waves
• Interface-induced field-like optical spin torque in a ferromagnet/heavy metal heterostructure
• Light-induced torque in ferromagnetic metals via orbital angular momentum generated by photon-helicity
• Off-resonant all-optical switching dynamics in a ferromagnetic model system
• Magnetoelectric effect in band insulator-ferromagnet heterostructures
• Laser-induced torques in spin spirals