Tailoring Magnetic Frustration in Strained Epitaxial FeRh Films

TL;DR

This study demonstrates how strain-induced structural transformations in epitaxial FeRh films suppress magnetic order by altering lattice symmetry and magnetic interactions, revealing new pathways to control magnetism via strain engineering.

Contribution

It uncovers a strain-driven martensitic transformation in FeRh films that causes magnetic suppression, highlighting a novel mechanism involving band-Jahn-Teller lattice instability.

Findings

Strain induces a cubic to tetragonal and then orthorhombic transition.

Structural change leads to collapse of magnetic order.

Magnetic suppression results from altered Fe-Rh hybridization and frustrated antiferromagnetic interactions.

Abstract

We report on a strain-induced martensitic transformation, accompanied by a suppression of magnetic order in epitaxial films of chemically disordered FeRh. X-ray diffraction, transmission electron microscopy and electronic structure calculations reveal that the lowering of symmetry (from cubic to tetragonal) imposed by the epitaxial relation leads to a further, unexpected, tetragonal-to-orthorhombic transition, triggered by a band-Jahn-Teller-type lattice instability. The collapse of magnetic order is a direct consequence of this structural change, which upsets the subtle balance between ferromagnetic nearest-neighbor interactions arising from Fe-Rh hybridization and frustrated antiferromagnetic coupling among localized Fe moments at larger distances.