Ulrich Nowak
On the basis of spin model calculations, the dynamics of antiferromagnets is discussed and compared to that of ferromagnets. The magnetic field component of a THz laser excitation can excite antiferromagnetic magnon modes, for very large fields eventually leading even to switching [1]. Relativistic extensions of the Landau-Lifshitz-Gilbert equation like field-derivative torques [2] and inertial spin dynamics [3] lead to additional dynamic effects which can facilitate switching in the THz regime.
Furthermore, we explore the possibility of ultrafast, coherent all-optical magnetization switching by studying the action of the inverse Faraday effect in CrPt, an easy-plane antiferromagnet. Using a combination of density-functional theory and atomistic spin dynamics simulations, we show how a circularly polarized laser pulse can switch the order parameter of the antiferromagnet within a few hundred femtoseconds. This nonthermal switching takes place on an elliptical path, driven by the staggered magnetic moments induced by the inverse Faraday effect, leading to reliable switching between two perpendicular magnetic states [4].
[2] R. Mondal et al., Phys. Rev. B 100, 060409 (R) (2019)
[3] R. Mondal et al., Phys. Rev. B 103, 104404 (2021)
[4] T. Dannegger et al., Phys. Rev. B 104, L060413 (2021)