Daria Gorelova
We developed a quantum-mechanical approach to derive equations of motion for magnetic vectors under the influence of an ultrashort light pulse [1]. Within our approach, the opto-magnetic effect caused by a light pulse on a magnetic system is described by a time-dependent magnetic operator that separates the effect of the laser pulse on the magnetic system from other magnetic interactions. We model and compare laser-induced precessions of magnetic sublattices of easy-plane and easy-axis antiferromagnetic systems. Using these models, we show how the ultrafast inverse Faraday effect induces a net magnetic moment in antiferromagnets and demonstrate that a crystal field environment and the exchange interaction play essential roles for laser-induced magnetization dynamics even during the action of a pump pulse. Suprisingly, light-induced precessions can start even during the action of the pump pulse with a duration several tens times shorter than the period of induced precessions and affect the position of magnetic vectors after the action of the pump pulse.
[1] Daria Popova-Gorelova, Andreas Bringer, and Stefan Blügel, Phys. Rev. B 104, 224418 (2021)