Quantifying octahedral rotations in strained perovskite oxide films

TL;DR

This paper introduces a method using x-ray diffraction to measure oxygen positions and octahedral rotations in strained perovskite oxide films, combining experimental data with ab initio calculations.

Contribution

It provides a general approach to quantify atomic structure changes in strained oxide films, specifically addressing the challenge of measuring oxygen positions.

Findings

Quantified octahedral rotations in LaNiO3 films under strain

Demonstrated the effectiveness of combining x-ray diffraction with ab initio calculations

Revealed how strain systematically alters atomic structure in perovskite oxides

Abstract

Epitaxial strain is a proven route to enhancing the properties of complex oxides, however, the details of how the atomic structure accommodates strain are poorly understood due to the difficulty of measuring the oxygen positions in thin films. We present a general methodology for determining the atomic structure of strained oxide films via x-ray diffraction, which we demonstrate using LaNiO3 films. The oxygen octahedral rotations and distortions have been quantified by comparing the intensities of half-order Bragg peaks, arising from the two unit cell periodicity of the octahedral rotations, with the calculated structure factor. Combining ab initio density functional calculations with these experimental results, we determine systematically how strain modifies the atomic structure of this functional oxide.