Strain, Young's modulus, and structural transition of EuTiO3 thin films probed by micro-mechanical methods

TL;DR

This study uses micro-mechanical methods to analyze EuTiO3 thin films, revealing their mechanical properties, strain behavior, and phase transition characteristics, including hysteresis and effects of oxygen vacancies.

Contribution

It demonstrates the fabrication and mechanical characterization of suspended EuTiO3 micro-structures, providing new insights into their strain, Young's modulus, and phase transition behavior.

Findings

EuTiO3 thin films exhibit non-monotonic, hysteretic mechanical responses during phase transition.

Oxygen vacancies significantly influence the mechanical properties of EuTiO3 films.

Comparison with literature helps distinguish thermal and softening effects on mechanical tuning.

Abstract

EuTiO3 (ETO) is a well-known complex oxide mainly investigated for its magnetic properties and its incipient ferro-electricity. In this work, we demonstrate the realization of suspended micro-mechanical structures, such as cantilevers and micro-bridges, from 100 nm-thick single-crystal epitaxial ETO films deposited on top of SrTiO3(100) substrates. By combining profile analysis and resonance frequency measurements of these devices, we obtain the Young's modulus, strain, and strain gradients of the ETO thin films. Moreover, we investigate the ETO anti-ferro-distorsive transition by temperature-dependent characterizations, which show a non-monotonic and hysteretic mechanical response. Comparison between experimental and literature data allows us to weight the contribution from thermal expansion and softening to the tuning slope, while a full understanding of the origin of such a wide hysteresis is still missing. We also discuss the influence of oxygen vacancies on the reported mechanical properties by comparing stoichiometric and oxygen-deficient samples.