All-optical magnetization switching in ferrimagnetic alloys: deterministic vs thermally activated dynamics

TL;DR

This study uses advanced microscopy to explore the mechanisms of all-optical magnetization switching in GdFe ferrimagnetic alloys, revealing how coercivity and temperature influence repeatability and demonstrating switching under magnetic fields.

Contribution

It provides new insights into the dynamics of AOS, highlighting the roles of thermal activation and temperature compensation in ferrimagnetic alloys.

Findings

Low coercivity limits AOS repeatability due to domain wall motion.

AOS occurs below and above the magnetization compensation temperature.

AOS can be achieved against magnetic fields up to 180 mT.

Abstract

Using photo-emission electron microscopy with X-ray magnetic circular dichroism as a contrast mechanism, new insights into the all-optical magnetization switching (AOS) phenomenon in GdFe based rare-earth transition metal ferrimagnetic alloys are provided. From a sequence of static images taken after single linearly polarized laser pulse excitation, the repeatability of AOS can be measured with a correlation coefficient. It is found that low coercivity enables thermally activated domain wall motion, limiting in turn the repeatability of the switching. Time-resolved measurement of the magnetization dynamics reveal that while AOS occurs below and above the magnetization compensation temperature $T_\text{M}$, it is not observed in GdFe samples where $T_\text{M}$ is absent. Finally, AOS is experimentally demonstrated against an applied magnetic field of up to 180 mT.