Magnetoelastic fingerprints of metamagnetism in FeRh

Recently, there has been renewed interest in the magnetism of FeRh that extends well beyond the extensively studied, yet not fully understood, antiferromagnetic–ferromagnetic transition. Despite its popularity, fundamental magnetic properties—including magnetocrystalline anisotropy and magnetoelasticity—remain insufficiently characterized from both theoretical and experimental studies. In this work, we first used Density Functional Theory to analyze these properties in single crystal FeRh for both antiferromagnetic and ferromagnetic phases at zero temperature, revealing significant qualitative and quantitative differences between them. We then attempted to develop a magnetic interatomic potential for a classical spin-lattice model, coupling spin dynamics and molecular dynamics, that reproduces the magnetoelastic phenomenology obtained from first principles calculations. Our results constitute a step towards a better understanding of the complex magnetoelasticity of FeRh and open the door to more accurate large-scale atomistic modeling of similar materials undergoing antiferromagnetic-ferromagnetic first-order phase transitions.