Anisotropy induced spin re-orientation in chemically-modulated amorphous ferrimagnetic films

TL;DR

This study demonstrates a temperature-driven, tunable spin re-orientation in amorphous ferrimagnetic RE-TM alloy films, enabling potential applications in thermal sensors and topological spin texture manipulation.

Contribution

It reveals how nanoscale chemical composition modulation induces sharp, temperature-dependent spin re-orientation in amorphous ferrimagnetic films, a novel mechanism for magnetic control.

Findings

Temperature-driven spin re-orientation observed in FeGd films.

Nanoscale chemical modulation explains the re-orientation transition.

Sharp two-step magnetic reversal mechanism identified.

Abstract

The ability to tune the competition between the in-plane and out-of-plane orientation of magnetization provides a means to construct thermal sensors with a sharp spin re-orientation transition at specific temperatures. We have observed such a tuneable, temperature driven spin re-orientation in structurally amorphous, ferrimagnetic rare earth-transition metal (RE-TM) alloy thin films using scanning transmission X-ray microscopy (STXM) and magnetic measurements. The nature of the spin re-orientation transition in FeGd can be fully explained by a non-equilibrium, nanoscale modulation of the chemical composition of the films. This modulation leads to a magnetic domain pattern of nanoscale speckles superimposed on a background of in-plane domains that form Laudau configurations in micron-scale patterned elements. It is this speckle magnetic structure that gives rise to a sharp two step-reversal mechanism that is temperature dependent. The possibility to balance competing anisotropies through the temperature opens opportunities to create and manipulate topological spin textures.