Large isosymmetric reorientation of oxygen octahedra rotation axes in epitaxially strained perovskites

TL;DR

This study uses first-principles calculations to reveal a large, strain-induced reorientation of oxygen octahedra in perovskites, enabling new ways to engineer their electronic properties.

Contribution

It uncovers an anomalously large isosymmetric reorientation of octahedral axes driven by strain, highlighting a new mechanism for tuning perovskite functionalities.

Findings

Large bi-axial strain causes octahedral axis reorientation.

Transition occurs between isosymmetric structures with different tilt magnitudes.

Many perovskites can exhibit this transition in thin films.

Abstract

Using first-principles density functional theory calculations, we discover an anomalously large bi-axial strain-induced octahedral rotation axis reorientation in orthorhombic perovskites with tendency towards rhombohedral symmetry. The transition between crystallographically equivalent (isosymmetric) structures with different octahedral rotation magnitudes originates from strong strain--octahedral rotation coupling available to perovskites and the energetic hierarchy among competing octahedral tilt patterns. By elucidating these criteria, we suggest many functional perovskites would exhibit the transition in thin film form, thus offering a new landscape in which to tailor highly anisotropic electronic responses.