Symmetry-driven atomic rearrangement at a brownmillerite-perovskite interface

TL;DR

This study reveals how symmetry mismatch at the interface of SrTiO3 and SrCoO2.5 causes atomic displacements that influence material properties, aiding the design of advanced oxide heterostructures.

Contribution

It provides detailed atomic-level mapping of interface structures between dissimilar oxides with different symmetries, highlighting the role of symmetry mismatch in atomic displacements.

Findings

Atomic displacements are confined to the first few atomic layers.

Symmetry mismatch induces unique atomic displacements at the interface.

Understanding these displacements can inform the design of functional oxide heterostructures.

Abstract

Many of the recent advancements in oxide heterostructures have been attributed to modification of spin, charge, lattice, and orbital order parameters at atomically well-defined interfaces. However, the details on the structural, chemical, and electrostatic evolution of interfaces comprised of materials with different crystallographic symmetries remain to be understood. In this work, we have mapped out the interfacial connectivity of atoms of two dissimilar materials, the perovskite SrTiO3 and the brownmillerite SrCoO2.5, using high resolution scanning transmission electron microscopy and geometric phase analysis. We observed unique symmetry-mismatch driven atomic displacements restricted to only the first few atomic layers, which can critically modify the properties of the system. Provided that SrCoO2.5 is a promising energy material due to its open framework structure, the improved understanding of the interfacial structure on the atomic level can lead to the rational design of novel oxide heterostructures.