Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 83: Topological Insulators III (joint session DS, HL, MA, O, TT, organized by HL)
TT 83.4: Talk
Friday, March 24, 2017, 10:15–10:30, POT 251
Double topological surface states in strained alpha-Sn — •Victor Rogalev1, Tomáš Rauch2, Markus Scholz1, Felix Reis1, Lenart Dudy1, Andrzej Fleszar3, Marius-Adrian Husanu4, Vladimir Strocov4, Jürgen Henk2, Ingrid Mertig2,5, Jörg Schäfer1, and Ralph Claessen1 — 1Physikalisches Institut und Röntgen Center for Complex Materials Systems, Universität Würzburg, 97074 Würzburg, Germany — 2Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany — 3Institut für Theoretische Physik und Astronomie, Universität Würzburg, 97074 Würzburg, Germany — 4Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland — 5Max Planck Institute for Microstructure Physics, 06120 Halle (Saale), Germany
The low temperature phase of Sn, α -Sn, is a semimetal with two pairs of "inverted" bands and zero energy band gap, which can be increased by strain. Experimental works revealed so far only one topological surface state (TSS) that bridges one pair of inverted bands.
By means of a combined experimental and theoretical approach we show that the electronic structure of the compressively strained α -Sn (001) thin film hosts an additional TSS in the valence band due to the second band inversion. This sub-surface localized TSS is directly accessed by soft X-ray angle-resolved photoemission with high probing depth. The second TSS reveals a much stronger hybridization with bulk states, in contrast to the already known surface-localized TSS. We show that such difference is consistent with the analysis of orbital composition of bulk and surface states.