Ab Initio Study of Helicity-Dependent Light-Induced Demagnetization: From the Optical Regime to the Extreme Ultraviolet Regime

We use ab initio real-time time-dependent density functional theory to investigate the effect of optical and extreme ultraviolet (XUV) circularly polarized femtosecond pulses on the magnetization dynamics of ferromagnetic materials. We demonstrate that the light induces a helicity-dependent reduction of the magnitude of the magnetization. In the XUV regime, where the 3p semicore states are involved, a larger helicity dependence persisting even after the passage of light is exhibited. Finally, we were able to separate the part of the helicity-dependent dynamics due to the absorption from the part due to the inverse Faraday effect. Doing so, we show that the former has, overall, a greater impact on the magnetization than the latter, especially after the pulse and in the XUV regime. This work hints at the yet experimentally unexplored territory of the XUV light-induced helicity-dependent dynamics, which, according to our prediction, could magnify the helicity-dependent dynamics already exhibited in the optical regime.

Automated summary

This research utilized ab initio real-time time-dependent density functional theory to study the impact of optical and extreme ultraviolet circularly polarized femtosecond pulses on the magnetization dynamics of ferromagnetic materials. It was found that the light-induced helicity-dependent reduction of magnetization was more pronounced in the XUV regime, where 3p semicore states were involved. The study also separated the effects of absorption and the inverse Faraday effect on magnetization dynamics, showing that the former had a greater impact overall, especially in the XUV regime.