Analogies of structural instabilities in EuTiO3 and SrTiO3

TL;DR

This study uncovers a new phase transition in EuTiO3 at 282K, similar to SrTiO3's transition at 105K, linked through soft phonon modes and influenced by spin-phonon coupling, highlighting structural instability analogies.

Contribution

It identifies a previously unknown phase transition in EuTiO3 and demonstrates its analogy to SrTiO3 through phonon mode analysis and theoretical modeling.

Findings

EuTiO3 exhibits a specific heat anomaly at 282K.

The soft phonon modes in EuTiO3 and SrTiO3 are modeled with identical parameters.

Spin-phonon coupling raises EuTiO3's transition temperature.

Abstract

Specific heat measurements and theoretical calculations reveal an intimate analogy between EuTiO3 and SrTiO3. For EuTiO3 a hitherto unknown specific heat anomaly is discovered at TA=282(1)K which is analogous to the well known specific heat anomaly of SrTiO3 at TA=105K caused by an antiferrodistortive transition. Since the zone center soft phonon mode observed in both systems can be modeled with the same parameters we ascribe the new 282(1)K instability of EuTiO3 to an antiferrodistortive phase transition. The higher transition temperature of EuTiO3 as compared to SrTiO3 results from spin phonon coupling.