Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Topological Insulators III (joined session with TT)

MA 63.4: Vortrag

Freitag, 24. März 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 Mertig^2,5, 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.