Resonant amplification of the inverse Faraday effect magnetization dynamics of time reversal symmetric insulators

Abstract

All-optical helicity-dependent manipulations of magnetism have attracted broad attention in the context of ultrafast control of magnetic units. Here, we investigate the spin dynamics in time reversal symmetric insulators induced by strong circularly polarized light. We perform real-time time-dependent density functional theory calculations together with model Hamiltonian analyses for MoS2 and WS2 monolayers, which are exemplary spin-orbit-coupled time reversal symmetric insulators. We trace the evolution of dynamical spin states, starting from the Kramers-paired electronic ground state, and find that the induced magnetization exhibits a sharp resonance peak when the applied light frequency is close to half the spin-flipping energy gap. The resonance condition is secondarily affected by the field strength and the pulse width. We suggest that low-energy time reversal broken excitations of insulators can be pursued with a sharp frequency selection as another class of ultrafast phenomena.