Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 51: Poster: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 51.11: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster B

Growth studies and angle-resolved photoemission of Fe coatings on the topological Dirac semi-metal α-Sn — •Johannes Jehn, Victor Rogalev, Lenart Dudy, Jörg Schäfer, and Ralph Claessen — Physikalisches Institut und Röntgen Center for Complex Material Systems, Universität Würzburg, 97074 Würzburg, Germany

Topological materials like α-Sn exhibit a band inversion between the p-like conduction and s-like second valence bands. Being compressively strained in (001)-plane, α-Sn enters the Dirac semi-metal phase, with topological surface states (TSS) protected by time-reversal symmetry. A magnetic field breaks this symmetry and is expected to open a gap in the surface states.

We investigate the effect of Fe coatings deposited on α-Sn films grown in situ by MBE on InSb(001) substrates. In ARPES, α-Sn samples clearly show linear dispersing surface states with a Dirac point (DP) close to the Fermi level. The position of the DP is controlled by Te doping. Fe impurities are deposited flux-controlled on the surface of α-Sn films with a coverage ranging from sub-monolayer to several monolayers (determined from XPS). Theoretically, a ferromagnetic order mediated by the TSS might be conceivable in such samples. However, in ARPES we observe no gap opening at the DP within our resolution for all Fe coverages. We speculate that the presence of projected bulk states near the Fermi level disturbs the ferromagnetic coupling via the TSS.