Dynamic control of octahedral rotation in perovskites by defect engineering

TL;DR

This paper introduces a defect engineering strategy to dynamically control octahedral rotations in perovskites, enabling new functionalities by coupling defects to external electric fields.

Contribution

It proposes a novel method using point defects to manipulate oxygen octahedral rotations in $ABO_3$ perovskites, validated through density functional theory and lattice modeling.

Findings

Defects can induce local electric dipoles that couple to octahedral rotations.

Switching of rotational degrees of freedom can be achieved over long distances.

Guidelines for screening other systems for defect-based control are provided.

Abstract

Engineering oxygen octahedra rotation patterns in $ABO_3$ perovskites is a powerful route to design functional materials. Here we propose a strategy that exploits point defects that create local electric dipoles and couple to the oxygen sublattice, enabling direct actuation on the rotational degrees of freedom. This approach, which relies on substituting an $A$ site with a smaller ion, paves a way to couple dynamically octahedra rotations to external electric fields. A common antisite defect, $\mathrm{Al_{La}}$ in rhombohedral LaAlO$_3$ is taken as a prototype to validate the idea, with atomistic density functional theory calculations supported with an effective lattice model to simulate the dynamics of switching of the local rotational degrees of freedom to long distances. Our simulations provide an insight of the main parameters that govern the operation of the proposed mechanism, and allow to define guidelines for screening other systems where this approach could be used for tuning the properties of the host material.