Published February 17, 2022 | Version v1
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Landau levels as a probe for band topology in graphene moiré superlattices

  • 1. Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
  • 2. National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
  • 3. School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
  • 4. ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 200031, China

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Description

We propose Landau levels as a probe for the topological character of electronic bands in two-dimensional moiré superlattices. We consider two configurations of twisted double bilayer graphene (TDBG) that have very similar band structures, but show different valley Chern numbers of the flat bands. These differences between the AB-AB and AB-BA configurations of TDBG clearly manifest as different Landau level sequences in the Hofstadter butterfly spectra calculated using the tight-binding model. The Landau level sequences are explained from the point of view of the distribution of orbital magnetization in momentum space that is governed by the rotational C2 and time-reversal T symmetries. Our results can be readily extended to other twisted graphene multilayers and h-BN/graphene heterostructures thus establishing the Hofstadter butterfly spectra as a powerful tool for detecting the nontrivial valley band topology.

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References

Journal reference (Paper in which the data is described)
QuanSheng Wu, Jianpeng Liu, Yifei Guan, and Oleg V. Yazyev, Phys. Rev. Lett. 126, 056401(2021), doi: 10.1103/PhysRevLett.126.056401