Modeling exchange bias microscopically

TL;DR

This paper investigates a microscopic model of exchange bias in ferromagnet-antiferromagnet systems, focusing on how domain formation and anisotropy influence the exchange bias effect.

Contribution

It introduces a model where diluted antiferromagnetic domains, frozen during cooling, explain exchange bias and its dependence on anisotropy.

Findings

Exchange bias depends nontrivially on antiferromagnetic anisotropy.

Diluted antiferromagnetic domains carry remanent magnetization.

The model links domain behavior to exchange bias control.

Abstract

Exchange bias is a horizontal shift of the hysteresis loop observed for a ferromagnetic layer in contact with an antiferromagnetic layer. Since exchange bias is related to the spin structure of the antiferromagnet, for its fundamental understanding a detailed knowledge of the physics of the antiferromagnetic layer is inevitable. A model is investigated where domains are formed in the volume of the AFM stabilized by dilution. These domains become frozen during the initial cooling procedure carrying a remanent net magnetization which causes and controls exchange bias. Varying the anisotropy of the antiferromagnet we find a nontrivial dependence of the exchange bias on the anisotropy of the antiferromagnet.