Magnetization reversal processes in ErFe2/YFe2 exchange spring multilayer studied by xray magnetic circular dichroism

TL;DR

This study uses x-ray magnetic circular dichroism and computational modeling to investigate magnetization reversal in ErFe2/YFe2 multilayers, revealing temperature-dependent switching behaviors and a spin-flop transition mechanism.

Contribution

It provides new insights into the temperature-dependent magnetization reversal processes and the nature of spin-flop transitions in exchange-spring multilayers.

Findings

At T < 200 K, a single irreversible switching process is observed.

At T > 200 K, two types of switching processes occur, indicating a crossover.

Computational models show a spin-flop like reorientation transition explains high-temperature behavior.

Abstract

X-ray magnetic circular dichroism at the Er M4,5 edge is used to study the switching behavior of the hard ErFe2 layers in an epitaxial [ErFe2(70{\AA})/YFe2 (150{\AA})]{\times}25 exchange-spring superlattice. Magnetic hysteresis loops for the Er magnetization, at temperatures T < 200 K, reveal a switching behavior with a single type of irreversible switch corresponding to vertical exchange spring states. Experiments at T > 200 K reveal a crossover to a regime with two types of switching processes. Computational modelling for this system gives a semi-quantitative agreement with the experiment and reveals that the observed high temperature switching behavior is due to a spin-flop like reorientation transition. In contrast to conventional spin-flop transitions in antiferromagnets, in this exchange spring system the increase in anisotropy energy of the hard magnetic layers is overcome by the decrease in Zeeman energy of the soft layers. Computational studies also reveal the presence of transitions between vertical exchange spring and spin-flop states with a first-order character as well as continuous transitions between these states.