Off-resonant all-optical switching dynamics in a ferromagnetic model system

Abstract

We present a theoretical study of the effects of optical fields on a ferromagnetic model system of itinerant carriers that includes both magnetism at the level of a time-dependent mean-field and spin-orbit coupling. In the framework of this model, which contains a band gap and is similar to the one introduced by Qaiumzadeh et al. [Phys. Rev. B 88, 064416 (2013)] we investigate the inverse Faraday effect, i.e., how the magnetization of the ferromagnetic bands can be influenced by the helicity of off-resonant optical fields. The magnetization dynamics are calculated self-consistently by including a dynamic ferromagnetic splitting and the corresponding single-particle states. We study the magnetization dynamics for the case of a rapid ramping-up of an optical field that is off-resonant with respect to the gap and find that the magnetization switching occurs due to the interplay of the coherence between the spin-split ferromagnetic bands and incoherent scattering/dephasing processes.