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.
Highlights
The application of a magnetic field to an antiferromagnet can cause abrupt changes to its magnetic state.1 While such metamagnetic transitions have been known for a long time in materials such as FeCl2 (Ref. 2) and MnF2,3 it is their association with technologies such as magnetic cooling4 that has driven recent efforts to control metamagnetism in the room temperature range, and in accessible magnetic fields
We describe a “disordered local moment” 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 magnetization state
The AFM polarization is parallel to a weak applied field and flips perpendicularly only if the field exceeds a critical value.17. In this Rapid Communication we describe an ab initio spin density functional theory (SDFT)-based “local moment” theory for AFM to suit real materials where both itinerant and local spin effects are at play
Summary
The application of a magnetic field to an antiferromagnet can cause abrupt changes to its magnetic state.1 While such metamagnetic transitions have been known for a long time in materials such as FeCl2 (Ref. 2) and MnF2,3 it is their association with technologies such as magnetic cooling4 that has driven recent efforts to control metamagnetism in the room temperature range, and in accessible magnetic fields.
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