• 文献标题:   Observation of Electrically Tunable van Hove Singularities in Twisted Bilayer Graphene from NanoARPES
  • 文献类型:   Article
  • 作  者:   JONES AJH, MUZZIO R, MAJCHRZAK P, PAKDEL S, CURCIO D, VOLCKAERT K, BISWAS D, GOBBO J, SINGH S, ROBINSON JT, WATANABE K, TANIGUCHI T, KIM TK, CACHO C, LANATA N, MIWA JA, HOFMANN P, KATOCH J, ULSTRUP S
  • 作者关键词:   flat band, nanoarpes, twisted bilayer graphene, van der waals heterostructure, van hove singularity
  • 出版物名称:   ADVANCED MATERIALS
  • ISSN:   0935-9648 EI 1521-4095
  • 通讯作者地址:   Aarhus Univ
  • 被引频次:   1
  • DOI:   10.1002/adma.202001656 EA JUN 2020
  • 出版年:   2020

▎ 摘  要

The possibility of triggering correlated phenomena by placing a singularity of the density of states near the Fermi energy remains an intriguing avenue toward engineering the properties of quantum materials. Twisted bilayer graphene is a key material in this regard because the superlattice produced by the rotated graphene layers introduces a van Hove singularity and flat bands near the Fermi energy that cause the emergence of numerous correlated phases, including superconductivity. Direct demonstration of electrostatic control of the superlattice bands over a wide energy range has, so far, been critically missing. This work examines the effect of electrical doping on the electronic band structure of twisted bilayer graphene using a back-gated device architecture for angle-resolved photoemission measurements with a nano-focused light spot. A twist angle of 12.2 degrees is selected such that the superlattice Brillouin zone is sufficiently large to enable identification of van Hove singularities and flat band segments in momentum space. The doping dependence of these features is extracted over an energy range of 0.4 eV, expanding the combinations of twist angle and doping where they can be placed at the Fermi energy and thereby induce new correlated electronic phases in twisted bilayer graphene.