Dependence of Gd concentration for ultrafast double pulse thermally induced magnetization switching in GdFeCo

Femtosecond laser-driven ultrafast magnetization switching (TIMS) has garnered significant interest for its potential to achieve picosecond-scale control of magnetic states. This work challenges the conventional view by demonstrating that full thermal equilibrium between subsystems is not a prerequisite for initiating magnetization switching. In this work, the magnetization dynamics of GdFeCo alloys excited by two consecutive pulses at different Gd concentrations and the minimum interval between two consecutive pulse-triggered double TIMS is investigated using atomic spin dynamics and a two-temperature model. The results show that the change of Gd concentration significantly affects the minimum interval of triggered double TIMS in GdFeCo alloys. We further investigated the variation of the normalized equilibrium magnetization of double TIMS with Gd concentration and the interval between successive pulses. The results show that an increase in the interval between successive pulses leads to an increase in the equilibrium magnetization after triggering double TIMS.