TITLE

Evidence for topological band inversion of the phase change material Ge2Sb2Te5

AUTHOR(S)
Pauly, Christian; Liebmann, Marcus; Giussani, Alessandro; Kellner, Jens; Just, Sven; Sánchez-Barriga, Jaime; Rienks, Emile; Rader, Oliver; Calarco, Raffaella; Bihlmayer, Gustav; Morgenstern, Markus
PUB. DATE
December 2013
SOURCE
Applied Physics Letters;12/9/2013, Vol. 103 Issue 24, p243109
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We present an angle-resolved photoemission study of a ternary phase change material, namely Ge2Sb2Te5, epitaxially grown on Si(111) in the metastable cubic phase. The observed upper bulk valence band shows a minimum at [formula] being 0.3 eV below the Fermi level EF and a circular Fermi contour around [formula] with a dispersing diameter of 0.27-0.36 Å-1. This is in agreement with density functional theory calculations of the Petrov stacking sequence in the cubic phase which exhibits a topological surface state. The topologically trivial cubic Kooi-De Hosson stacking shows a valence band maximum at Γ in line with all previous calculations of the hexagonal stable phase exhibiting the valence band maximum at Γ for a trivial Z2 topological invariant ν0 and away from Γ for non-trivial ν0. Scanning tunneling spectroscopy exhibits a band gap of 0.4 eV around EF.
ACCESSION #
92961797

 

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