Stoichiometry effect on the structure and phase of antiperovskite Sr3SnO thin films prepared using combinatorial co-sputtering

Abstract

The observation of superconductivity in antiperovskite Sr3SnO crystals has sparked significant interest in understanding its underlying mechanism and fabricating them in thin film forms. To date, molecular beam epitaxy has been used to prepare Sr3SnO thin films, but superconductivity has not been observed. Sr deficiency and subsequent hole doping have been suggested as crucial for the emergent superconductivity, but difficulty in sample preparation due to high chemical instability of this material system has posed challenges for systematic and extensive studies. In this study, we report the fabrication of Sr3SnO thin films through co-sputtering of Sr and SnO2 and investigate the stoichiometry effect on the structural properties of Sr3SnO thin films using a combinatorial approach. A single Sr3SnO phase is observed over a wide range of off-stoichiometric Sr/Sn ratio regions, with preferred orientation changing depending on the Sr/Sn ratio. The formation of intermetallic Sr–Sn compounds in highly Sr-deficient regions suggests the need for careful consideration in elucidating the origin of superconductivity. The single orientation along the [002] direction and lattice parameter change due to biaxial strain applied by using a LAO substrate are indicative of the possible epitaxial growth of antiperovskite oxides using sputtering. Our experimental approach and findings pave the way for high-throughput preparation and characterization of antiperovskite oxides, thus encouraging research on antiperovskite oxides as well as other exotic materials involving highly reactive elements.