Minimum separation between two pump pulses for ultrafast double magnetization switching in GdFeCo

Abstract

Femtosecond laser ultrafast thermally induced magnetization switching (TIMS) has also attracted much attention due to its ability to trigger a single switching at the picosecond timescale. Current studies have shown that after a TIMS excited by a laser pulse, excitation of the switch again via TIMS does not require equilibrium between the subsystems. In this work, the main investigation is on the various possible cases of magnetization dynamics in GdFeCo under two short-delayed pulse excitations, as well as the factors limiting the minimum separation for double TIMS. These conditions are relevant for the potential application of TIMS to memory devices as it affects both the speed limit at which rewritten data is available and demonstrates the importance of spatial confinement of a laser pulse to bit size. The results show that low energy and short pulse duration lasers are prerequisites for double TIMS in GdFeCo based on simulations of atomic spin dynamics. By changing the damping constants of the alloy, we can shorten the minimum pulse separation between two pump pulses for double TIMS to 2 ps to approach terahertz frequency of write/erase cycles.