STM study of Stanene

The tin analog to graphene, stanene, is predicted to be a Quantum Spin Hall Insulator whereas, stanane is anticipated to behave as a trivial insulator. This suggests that tuning the physical properties of stanene could be achieved by direct modification of the surface. However, experimentally realizing stanene has been challenging as the parent crystal cannot be exfoliated and growing the material directly requires molecular beam epitaxy. Here we present Scanning Tunneling Microscopy study of stanene and its surface alloy on Cu(111). By thermal evaporation we deposited sub-monolayer coverage of tin on the surface. We observe a triangular lattice with 4.6Å spacing, consistent with the upward sites of the buckled honeycomb structure of stanene as calculated by DFT. Co-adsorbed on the surface a 5.2Å lattice, consistent with a 2x2 reconstruction of the Cu(111) surface, indicates a CuSn alloy. Tunneling spectroscopy on stanene do not clearly show the anticipated spin-orbit gap, and we see contributions of the underlying Cu(111) states, similar to what we previously reported for graphene. Consequently, we show progress towards isolating stanene with an in-situ growth of a hexagonal boron nitride buffer layer.