2020, Herrmann, Hannes, Hlawenka, Peter, Siemensmeyer, Konrad, Weschke, Eugen, Sánchez-Barriga, Jaime, Varykhalov, Andrei, Shitsevalova, Natalya Y., Dukhnenko, Anatoliy V., Filipov, Volodymyr B., Gabáni, Slavomir, Flachbart, Karol, Rader, Oliver, Sterrer, Martin, Rienks, Emile D.L.

SmB6 has recently attracted considerable interest as a candidate for the first strongly correlated topological insulator. Such materials promise entirely new properties such as correlation-enhanced bulk bandgaps or a Fermi surface from spin excitations. Whether SmB6 and its surface states are topological or trivial is still heavily disputed however, and a solution is hindered by major disagreement between angle-resolved photoemission (ARPES) and scanning tunneling microscopy (STM) results. Here, a combined ARPES and STM experiment is conducted. It is discovered that the STM contrast strongly depends on the bias voltage and reverses its sign beyond 1 V. It is shown that the understanding of this contrast reversal is the clue to resolving the discrepancy between ARPES and STM results. In particular, the scanning tunneling spectra reflect a low-energy electronic structure at the surface, which supports a trivial origin of the surface states and the surface metallicity of SmB6. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim