Universal Criteria for Single Femtosecond Pulse Ultrafast Magnetization Switching in Ferrimagnets

Single-pulse switching has been experimentally demonstrated in ferrimagnetic GdFeCo and Mn2RuxGaalloys. Complete understanding of single-pulse switching is missing due to the lack of an established theoryaccurately describing the transition to the nonequilibrium reversal path induced by femtosecond laserphotoexcitation. In this work, we present general macroscopic theory for the magnetization dynamics offerrimagnetic materials upon femtosecond laser excitation. Our theory reproduces quantitatively all stagesof the switching process observed in experiments. We directly compare our theory to computer simulationsusing atomistic spin dynamics methods for both GdFeCo and Mn2RuxGa alloys. We provide explicitexpressions for the magnetization relaxation rates in terms of microscopic parameters, which allows us topropose universal criteria for switching in ferrimagnets.

Automated summary

In this work, a general macroscopic theory for the magnetization dynamics of ferrimagnetic materials upon femtosecond laser excitation is proposed. By comparing with computer simulations, explicit expressions for the magnetization relaxation rates are obtained, and universal criteria for switching in ferrimagnets are proposed.