Atomistic spin-model based on a new spin-cluster expansion technique: Application to the IrMn3/Co interface

TL;DR

This paper introduces a new computational approach combining Spin-Cluster Expansion and the Relativistic Disordered Local Moment scheme to accurately calculate magnetic interactions and anisotropies at interfaces, exemplified by IrMn3/Co.

Contribution

The paper presents a novel method for deriving tensorial exchange interactions and anisotropies in itinerant magnetic systems, applied to the IrMn3/Co interface.

Findings

Limited magnetic coupling near the interface

Calculated site-resolved anisotropies

Identified Dzyaloshinskii-Moriya interactions at the interface

Abstract

In order to derive tensorial exchange interactions and local magnetic anisotropies in itinerant magnetic systems, an approach combining the Spin-Cluster Expansion with the Relativistic Disordered Local Moment scheme is introduced. The theoretical background and computational aspects of the method are described in detail. The exchange interactions and site resolved anisotropy contributions for the IrMn3/Co(111) interface, a prototype for an exchange bias system, are calculated including a large number of magnetic sites from both the antiferromagnet and ferromagnet. Our calculations reveal that the coupling between the two subsystems is fairly limited to the vicinity of the interface. The magnetic anisotropy of the interface system is discussed, including effects of the Dzyaloshinskii-Moriya interactions that appear due to symmetry breaking at the interface.