Regensburg 2019 – scientific programme
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O: Fachverband Oberflächenphysik
O 66: Poster Wednesday: 2D Materials
O 66.10: Poster
Wednesday, April 3, 2019, 17:45–20:00, Poster B2
Layer dependent properties of quasi-freestanding 2H-TaS2 investigated with STM and STS — •Camiel van Efferen1, Joshua Hall1, Clifford Murray1, Matthias Rolf1, Niels Ehlen1, Jun Li1, Jan Berges2, Erik van Loon2, Tim Wehling2, Alexander Grüneis1, and Thomas Michely1 — 1II. Physikalisches Institut, Universität zu Köln, Germany — 2Institut für Theoretische Physik, Bremen Center for Computational Materials Science, Universität Bremen, Germany
We epitaxially grow quasi-freestanding TaS2 multilayers on graphene on Ir(111) and investigate their thickness dependent properties up to three layers.
Using scanning tunnelling microscopy we observe the monolayer to be in the expected 3 × 3 charge density wave (CDW) phase, whereas the bilayer unexpectedly shows a 2 × 2 superstructure. Furthermore, the moiré of Gr on Ir(111) is no longer visible through the bilayer. Due to finite bilayer island sizes confinement effects occur, which interact with the superstructure.
We probe the electronic structure with low temperature scanning tunnelling spectroscopy, and find a strongly decreased density of states around the Fermi energy, as would be expected for a CDW. The width of the gap is compared with its monolayer analogue.
We disentangle contributions from intrinsic bilayer properties, stacking effects and local confinement effects to the electronic structure.