Charge Inversion and Topological Phase Transition at a Twist Angle Induced van Hove Singularity of Bilayer Graphene

Youngwook Kim, Patrick Herlinger, Pilkyung Moon, Mikito Koshino, Takashi Taniguchi, Kenji Watanabe, Jurgen H. Smet

Research output: Contribution to journalArticlepeer-review

82 Citations (Scopus)

Abstract

van Hove singularities (VHS's) in the density of states play an outstanding and diverse role for the electronic and thermodynamic properties of crystalline solids. At the critical point the Fermi surface connectivity changes, and topological properties undergo a transition. Opportunities to systematically pass a VHS at the turn of a voltage knob and study its diverse impact are however rare. With the advent of van der Waals heterostructures, control over the atomic registry of neighboring graphene layers offers an unprecedented tool to generate a low energy VHS easily accessible with conventional gating. Here we have addressed magnetotransport when the chemical potential crosses the twist angle induced VHS in twisted bilayer graphene. A topological phase transition is experimentally disclosed in the abrupt conversion of electrons to holes or vice versa, a loss of a nonzero Berry phase and distinct sequences of integer quantum Hall states above and below the singularity.

Original languageEnglish
Pages (from-to)5053-5059
Number of pages7
JournalNano Letters
Volume16
Issue number8
DOIs
Publication statusPublished - 2016 Aug 10

Keywords

  • Moiré superlattice
  • Twisted bilayer graphene
  • topological transition
  • van Hove singularity

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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