Though single-pulse switching has been experimentally demonstrated in some ferrimagnetic alloys, complete understanding of single-pulse switching has been missing due to the lack of an established theory accurately describing the transition to the nonequilibrium reversal path induced by femtosecond laser photoexcitation.

Unai Atxitia, PI of the 1^st funding period of our TRR 227, and his coworker published their latest results in Phys. Rev. Lett., where they present a general macroscopic theory for the magnetization dynamics of ferrimagnetic materials upon femtosecond laser excitation. Furthermore, they provide explicit expressions for the magnetization relaxation rates in terms of microscopic parameters, which allows them to propose universal criteria for switching in ferrimagnets.

F. Jakobs and U. Atxitia: Universal criteria for single femtosecond pulse ultrafast magnetization switching in ferrimagnets - Phys. Rev. Lett. 129, 037203 (2022) - DOI: 10.1103/PhysRevLett.129.037203