Strain-induced structural instability in FeRh

Abstract

We perform density functional calculations to investigate the structure of the inter-metallic alloy FeRh under epitaxial strain. Bulk FeRh exhibits a metamagnetic transition from a low-temperature antiferromagnetic (AFM) phase to a ferromagnetic (FM) phase at 350K, and its strain dependence is of interest for tuning the transition temperature to the room-temperature operating conditions of typical memory devices. We find an unusually strong dependence of the structural energetics on the choice of exchange-correlation functional, with the usual local density approximation (LDA) yielding the wrong ground-state structure, and generalized gradient (GGA) extensions being in better agreement with the bulk experimental structure. Using the GGA we show the existence of a metastable face-centered-cubic (fcc)-like AFM structure that is reached from the ground state body-centered-cubic (bcc) AFM structure by following the epitaxial Bain path. We predict that this metastable fcc-like structure has a significantly higher conductivity than the bcc AFM phase. We show that the behavior is well described using non-linear elasticity theory, which captures the softening and eventual sign change of the orthorhombic shear modulus under compressive strain, consistent with this structural instability. Finally, we predict the existence of an additional unit-cell-doubling lattice instability, which should be observable at low temperature.

arXiv comment10 pages, 7 figures

References in corpus (3)

• Room-temperature antiferromagnetic memory resistor
• Ab initio calculations of third-order elastic constants and related properties for selected semiconductors
• Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

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• High-speed metamagnetic resistive switching of FeRh through Joule heating
• Epitaxial strain adaption in chemically disordered FeRh thin films
• Mechanical stability of homogeneous holographic solids under finite shear strain
• Laser induced phase transition in epitaxial FeRh layers studied by pump-probe valence band photoemission
• Rare-earth-free noncollinear metallic ferrimagnets Mn4-xZxN with compensation at room temperature
• Depth Profile of the Phase Transition of the FeRh Alloy in FeRh/BaTiO3