Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 39: Poster Tuesday: 2D Materials
O 39.2: Poster
Dienstag, 2. April 2019, 18:00–20:00, Poster D
Intricacies in Twisted bilayer graphene: Structural or Electronic? — •Birce Sena Tömekce1, Büsra Gamze Arslan1, Oguzhan Gürlü1,2, and Dilek Yildiz1,2 — 1Istanbul Technical University, Department of Physics, 34460, Istanbul, Turkey — 2Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
Electronic and morphological properties of twisted bilayer graphene strongly depend on the rotation angle between the layers. Super periodic structures called as moire patterns are formed as a result of such rotation. However, properties of single/bilayer graphene may be modified due to unintentional doping by the substrate or due to the stress that is induced by lattice mismatch between graphene and the substrate. We prepared moire structures on highly oriented pyrolytic graphite (HOPG) by rotating the topmost graphene layer. This way we avoid the effect of the substrate on the final bilayer as the graphene is on its native surface. We studied the electronic and morphological properties of different moire patterns on graphene/HOPG system by means of scanning tunneling microscopy (STM) and spectroscopy (STS). We studied apparent corrugations of different moire patterns as a function of bias voltage in order to compare the electronic properties of moire patterns as a function of their periodicities [1]. In this work we discuss the formation mechanism of moire patterns in HOPG surfaces. We also show that moire patterns are mostly electronic if the rotation angle of the topmost graphene layer is relatively large and they are structural if the rotation angle is comparatively small. [1] D. Yildiz and O. Gürlü, Mater. Today Commun., 8 (2016), pp. 72-78