Structural properties of strained epitaxial La_1+δCrO₃ thin films

Epitaxially strained La_1+δCrO₃ (LCO) thin films, with δ ranging between −0.25 (Cr-rich) and 0.25 (La-rich), were grown on SrTiO₃(001) substrates by solid-source molecular beam epitaxy. The effect of the cationic-stoichiometry deviation (δ) on the structural properties (surface structure, morphology, terminations, and unit-cell parameters) is reported. Whereas deviation from stoichiometry does not significantly affect the structural quality (all films keep a perovskite structure, are epitaxial, atomically flat, fully strained, and present mosaicity below 0.1°); increasing |δ| leads to an increase of the out-of-plane lattice parameter and of the unit-cell volume. These results are of importance for further studies on structure–property relationships in the view to build enhanced LCO-based devices.