Tuning the metamagnetism of an antiferromagnetic metal

TL;DR

This paper introduces a first-principles theory showing how local moment interactions in an antiferromagnetic metal can lead to tricritical metamagnetism, with implications for designing materials for magnetic cooling.

Contribution

It presents a novel disordered local moment model that predicts temperature-dependent metamagnetic behavior in antiferromagnetic metals, linking electronic structure to magnetic phase transitions.

Findings

Accurately predicts critical fields in CoMnSi alloys

Explains sensitivity of metamagnetism to atomic separations

Provides a framework for designing new metamagnets

Abstract

We describe a `disordered local moment' (DLM) first-principles electronic structure theory which demonstrates that tricritical metamagnetism can arise in an antiferromagnetic metal due to the dependence of local moment interactions on the magnetisation state. Itinerant electrons can therefore play a defining role in metamagnetism in the absence of large magnetic anisotropy. Our model is used to accurately predict the temperature dependence of the metamagnetic critical fields in CoMnSi-based alloys, explaining the sensitivity of metamagnetism to Mn-Mn separations and compositional variations found previously. We thus provide a finite-temperature framework for modelling and predicting new metamagnets of interest in applications such as magnetic cooling.