Molecular beam epitaxy of phase-pure antiperovskite Sr3SnO thin films

Abstract

The antiperovskite oxide Sr3SnO has attracted substantial interest due to its topologically non-trivial band structure. Sr-deficient Sr3-xSnO can become superconducting, making it a candidate intrinsic topological superconductor. Here, we show that epitaxial, phase-pure Sr3-xSnO films can be synthesized by molecular beam epitaxy (MBE) using solid Sr and SnO2 sources. We show that Sn-rich growth conditions result in a large amount of a Sn-rich impurity phase, which is challenging to detect in x-ray diffraction. Carrier densities and the amount of the impurity phase change systematically with the growth conditions, indicating that MBE provides excellent control over the films' stoichiometry. We discuss the electrical properties, including quantum interference phenomena, which support the topological nature of the films.