Effects of Antiferromagnetic Spin Rotation on Anisotropy of Ferromagnetic/Antiferromagnetic Bilayers

TL;DR

This study investigates how antiferromagnetic spin rotation influences the magnetic anisotropy in NiFe/FeMn bilayers, revealing distinct behaviors in exchange bias and coercivity linked to anisotropy variations with temperature.

Contribution

It provides a quantitative analysis of anisotropy behaviors in bilayers, highlighting the role of antiferromagnetic spin rotation in magnetic properties.

Findings

Unidirectional anisotropy observed in thick FeMn layers.

Enhanced coercivity linked to rotatable magnetic anisotropy.

Temperature affects anisotropy behaviors.

Abstract

In epitaxial (111) oriented Ni$_{80}$Fe$_{20}$/Fe$_{50}$Mn$_{50}$ bilayers, we separate two distinct behaviors: unidirectional anisotropy (exchange bias) in thick Fe$_{50}$Mn$_{50}$, and enhanced coercivity in thin Fe$_{50}$Mn$_{50}$. By measuring the magnetization response to a rotating magnetic field, we quantitatively determine the relevant anisotropies, and demonstrate that the enhanced coercivity is related to the rotatable magnetic anisotropy of Fe$_{50}$Mn$_{50}$. We also demonstrate the consequences of the anisotropy changes with temperature.