Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 1: Tutorial: 2D Quantum Materials and Heterostructures: From Fabrication to Applications (joint session HL/TUT)
HL 1.2: Tutorium
Sonntag, 4. September 2022, 16:35–17:10, H2
Non-identical moire twins in bilayer graphene — •Rebeca Ribeiro-Palau1, Everton Arrighi1, Viet-Hung Nguyen2, Mario Di Luca1, Gaia Maffione1, Kenji Watanabe3, Takashi Taniguchi3, Dominique Mailly1, and Jean-Christophe Charlier2 — 1Universite Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies (C2N), 91120 Palaiseau, France — 2Institute of Condensed Matter and Nanosciences, Universite catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium — 3National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan
I will present recent results which demonstrate that the moire superlattice formed by a bilayer graphene aligned with BN, is present every 60 deg, but the symmetry is broken between the 0 deg and 60 deg alignments, creating non-identical "moire twins" with different electronic properties. In particular, electron transport measurements display a fully developed valley Hall effect at 0 deg while on the contrary, it is completely absent at 60 deg. We explain this effect by performing numerical simulations, which highlight the central role of the atomic-scale structural relaxation of the second graphene layer. This in-plane atomic relaxation, different for the two alignments, impacts on the electronic band structure of our system. Our results demonstrate that in situ control of the rotational order provides a unique insight on the interplay between mechanical and electronic properties, and increases the posibilities for band-structure engineering on van der Waals heterostructures.