Evidence for the first-order nature of the structural instability in EuTiO3 from thermal expansion measurements

The structural phase transition of EuTiO3 near T-S = 282 K is investigated by temperature-and magnetic-field-dependent measurements of the linear thermal expansion (TE) on a polycrystalline sample. At T-S a distinct anomaly is seen in the linear coefficient which is similar to the anomaly seen at the cubic-to-tetragonal phase transition in SrTiO3. The anomaly is well described by the thermal displacement correlation function which exhibits an abrupt change at the structural phase transition caused by a double-well potential in the oxygen-oxygen interaction. In accordance with previous data a pronounced magnetic-field effect on the TE is observed which might yield an alternative potential for applications.