# Oxygen vacancies in strained SrTiO$_{3}$ thin films: formation enthalpy and manipulation

## TL;DR

This study investigates how epitaxial strain affects oxygen vacancy formation in SrTiO₃ thin films, revealing that strain reduces formation energy and enables manipulation of vacancies and local properties via electric fields.

## Contribution

It provides new insights into the effects of strain on oxygen vacancy formation enthalpy and demonstrates electric field control of vacancy distribution and associated mechanical responses.

## Key findings

- Both compressive and tensile strain decrease vacancy formation enthalpy.
- Electric fields can modulate oxygen vacancy concentration locally.
- Vacancies influence TiO₆ octahedral rotation patterns.

## Abstract

We report the enthalpy of oxygen vacancy formation in thin films of electron-doped SrTiO$_{3}$, under different degrees of epitaxial stress. We demonstrate that both compressive and tensile strain decrease this energy at a very similar rate, and promote the formation of stable doubly ionized oxygen vacancies. Moreover, we also show that unintentional cationic vacancies introduced under typical growth conditions, produce a characteristic rotation pattern of TiO$_6$ octahedra. The local concentration of oxygen vacancies can be modulated by an electric field with an AFM tip, changing not only the local electrical potential, but also producing a non-volatile mechanical response whose sign (up/down) can be reversed by the electric field.