Topological surface states above the Fermi level in Hf2Te2P

Author(s): Boyle, TJ; Rossi, A; Walker, M; Carlson, P; Miller, MK; Zhao, J; Klavins, P; Jozwiak, C; Bostwick, A; Rotenberg, E; Taufour, V; Vishik, IM; da Silva Neto, EH | Abstract: © 2019 American Physical Society. We report a detailed experimental study of the band structure of the recently discovered topological material Hf2Te2P. Using the combination of scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy with surface K doping, we probe the band structure of Hf2Te2P with energy and momentum resolution above the Fermi level. Our experiments show the presence of multiple surface states with a linear Dirac-like dispersion, consistent with the predictions from previously reported band-structure calculations. In particular, scanning tunneling spectroscopy measurements provide experimental evidence for the strong topological surface state predicted at 460meV, which stems from the band inversion between Hf-d and Te-p orbitals. This band inversion comprised of more localized d states could result in a better surface-to-bulk conductance ratio relative to more traditional topological insulators.