In-plane magnetic reorientation in coupled ferro- and antiferromagnetic thin films

TL;DR

This paper investigates how the magnetic orientation in coupled ferromagnetic and antiferromagnetic thin films changes with temperature and thickness, revealing a reorientation driven by interlayer exchange interactions.

Contribution

It introduces a theoretical model showing how interlayer exchange coupling influences in-plane magnetic reorientation in coupled thin films.

Findings

Reorientation depends on temperature and film thickness.

Interlayer exchange coupling can be quantified via anisotropy measurements.

A canted magnetic state can mediate between collinear and orthogonal arrangements.

Abstract

By studying coupled ferro- (FM) and antiferromagnetic (AFM) thin film systems, we obtain an in-plane magnetic reorientation as a function of temperature and FM film thickness. The interlayer exchange coupling causes a uniaxial anisotropy, which may compete with the intrinsic anisotropy of the FM film. Depending on the latter the total in-plane anisotropy of the FM film is either enhanced or reduced. Eventually a change of sign occurs, resulting in an in-plane magnetic reorientation between a collinear and an orthogonal magnetic arrangement of the two subsystems. A canted magnetic arrangement may occur, mediating between these two extremes. By measuring the anisotropy below and above the N\'eel temperature the interlayer exchange coupling can be determined. The calculations have been performed with a Heisenberg-like Hamiltonian by application of a two-spin mean-field theory.