# Epitaxial strain adaption in chemically disordered FeRh thin films

## TL;DR

This study investigates how chemically disordered FeRh thin films adapt to epitaxial strain through tilting mechanisms, combining experimental techniques and density functional theory to reveal energetically favorable structural distortions.

## Contribution

It demonstrates a tilting strain adaptation mechanism in FeRh thin films and introduces a method using alloy buffer layers to study strain behaviors in detail.

## Key findings

- FeRh films adapt via tilting of structural units.
- Density functional theory confirms energetic favorability of c/a=0.87 distortion.
- Epitaxial buffer layers enable detailed strain behavior analysis.

## Abstract

Strain and strain adaption mechanisms in modern functional materials are of crucial importance for their performance. Understanding these mechanisms will advance innovative approaches for material properties engineering. Here we study the strain adaption mechanism in a thin film model system as function of epitaxial strain. Chemically disordered FeRh thin films are deposited on W-V buffer layers, which allow for large variation of the preset lattice constants, e.g. epitaxial boundary condition. It is shown by means of high resolution X-ray reciprocal space maps and transmission electron microscopy that the system reacts with a tilting mechanism of the structural units in order to adapt to the lattice constants of the buffer layer. This response explained by density functional theory calculations, which evidence an energetic minimum for structures with a distortion of c/a =0.87. The experimentally observed tilting mechanism is induced by this energy gain and allows the system to remain in the most favorable structure. In general, it is shown that the use of epitaxial model heterostructures consisting of alloy buffer layers of fully miscible elements and the functional material of interest allows to study strain adaption behaviors in great detail. This approach makes even small secondary effects observable, such as the directional tilting of the structural domains identified in the present case study.