Transverse instability at a compensated interface of ferromagnetic antiferromagnetic bilayer

TL;DR

This paper develops an analytical theory for ferromagnetic-antiferromagnetic bilayers with a compensated interface, revealing conditions for transverse instability and proposing stabilization methods to control exchange bias.

Contribution

It introduces an explicit expression for interfacial interaction energy and analyzes the stability of domain walls, highlighting the role of external magnetic fields and anisotropy.

Findings

Transverse instability occurs in antiferromagnetic films at high surface interaction strength.

External magnetic fields can induce out-of-plane deviations of the antiferromagnetic vector.

In-plane anisotropy can stabilize the spin distribution near the interface.

Abstract

The analytical theory for a ferromagnetic antiferromagnetic bilayer with a compensated interface has been developed using an explicit expression for the interfacial interaction energy density. A stability of a solution describing domain walls within ferromagnetic and antiferromagnetic films has been investigated. It is shown that even for high values of surface interaction strength a transverse instability originates within the antiferromagnetic film, because the deviation of the unit antiferromagnetic vector out of the interface plane becomes energetically favorable in large enough external magnetic field. However, it is possible to stabilize the spin distribution near the interface assuming additional in-plane anisotropy within the antiferromagnetic layer. In principle, this opens a way to control exchange bias just avoiding a complicated problem of domain rearrangement within the antiferromagnetic film.