Oksana Chubykalo-Fesenko
Novel possibilities for ultrafast magnetisation switching have been presented recently using ultrafast phonon excitations in Terahertz (THz) regime [1]. These results also suggest that at the picosecond timescale and below spin-phonon dynamics occur simultaneously and one system can excite another. Here we investigate the magnetisation dynamics in a spin-lattice model [2]parameterised for Fe under the application of a THz phonon pulse. The modeling is done within the molecular dynamics approach in a self-consistent spin-lattice framework. We demonstrate the possibility of a very energy efficient switching in the conditions when phonons are excited with high k-values and THz frequencies, corresponding to a maximum in the density of states and no possibility of spinwave excitation. The mechanism of switching
is via local magneto-elastic fields created by atom’s displacements. In the conditions of the absence of spinwave excitations, practically all phonon angular momentum is transferred to a precessional magnetisation switching. The spin temperature calculated during the switching
process shows a minimum increase (in the order of mK), hence the switching process can be considered non-dissipative. Finally, I will also discuss some very recent results on antiferromagnets.
[2] M.Strungary et al Phys Rev B 103 (2021) 024429