Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

TL;DR

This paper investigates the origin of the metamagnetic phase transition in alpha-FeRh, attributing it to the instability of rhodium's magnetic moment caused by competing magnetic states and exchange interactions, modeled through ab initio calculations and Monte Carlo simulations.

Contribution

It introduces a first-principle spin-based model that reproduces the metamagnetic transition and accounts for magneto-volume effects in alpha-FeRh.

Findings

Rhodium exhibits two magnetic states influencing the transition.

Competing ferromagnetic and antiferromagnetic interactions drive the phase change.

The model successfully reproduces experimental magneto-volume effects.

Abstract

Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A first-principle spin-based model allows to reproduce this first-order metamagnetic transition by means of Monte Carlo simulations. Further inclusion of spacial variation of exchange parameters leads to a realistic description of the experimental magneto-volume effects in alpha-FeRh.