Probing for Topological Superconductivity in In-doped SnTe

Recent investigations of 3D topological insulators, which have gapless surface states protected by time reversal symmetry, have drawn attention to the search for new topological states protected by other symmetries. Theories predicted the existence of topological crystalline insulators (TCIs), which have gapless surface states protected by symmetry of the crystal lattice. In this work, we use scanning tunneling spectroscopy to investigate the superconducting properties of indium-doped tin telluride (Sn$_{\mathrm{1-x}}$In$_{\mathrm{x}}$Te), which is predicted to be a topological crystalline insulator. In a sample with T$_{\mathrm{c}}\approx $1.6 K, the tunneling spectra show a superconducting gap of 0.2 meV, which is continuous throughout the surface of the cleaved crystal. The superconducting gap is suppressed at a critical magnetic field of B$=$0.50 T and dI/dV conductance maps reveal a vortex lattice in a perpendicular applied magnetic field. Measurements will be shown as a function of In doping and discussed in relation to predictions and experiments on topological superconductivity in this material.