Structural evolution of epitaxial SrCoOx films near topotactic phase transition

TL;DR

This study investigates the structural, electronic, and magnetic evolution of epitaxial SrCoOx films during topotactic phase transition, revealing significant property changes near the critical temperature while maintaining overall crystallinity.

Contribution

It provides detailed insights into the structural evolution of SrCoOx films during topotactic phase transition, highlighting the potential for reversible property control in complex oxides.

Findings

Significant changes in electronic transport and magnetism near the transition temperature.

Crystallinity remains intact despite phase transformation.

Topotactic control enables reversible tuning of physical properties.

Abstract

Control of oxygen stoichiometry in complex oxides via topotactic phase transition is an interesting avenue to not only modifying the physical properties, but utilizing in many energy technologies, such as energy storage and catalysts. However, detailed structural evolution in the close proximity of the topotactic phase transition in multivalent oxides has not been much studied. In this work, we used strontium cobaltites (SrCoOx) epitaxially grown by pulsed laser epitaxy (PLE) as a model system to study the oxidation-driven evolution of the structure, electronic, and magnetic properties. We grew coherently strained SrCoO2.5 thin films and performed post-annealing at various temperatures for topotactic conversion into the perovskite phase (SrCoO3-{\delta}). We clearly observed significant changes in electronic transport, magnetism, and microstructure near the critical temperature for the topotactic transformation from the brownmillerite to the perovskite phase. Nevertheless, the overall crystallinity was well maintained without much structural degradation, indicating that topotactic phase control can be a useful tool to control the physical properties repeatedly via redox reactions.