Tunable Moir\'{e} Bands in Minimally Twisted Bilayer Graphene.

ORAL

Abstract

We present the realization of tunable moir\'{e} crystals in minimally twisted (MT) bilayer graphene, and provide a comprehensive study of electron transport in these samples. In twisted bilayer graphene, the relative rotation of the two graphene layers leads to the formation of a new moir\'{e} crystal, which is expected to have a dramatically different band structure compared to Bernal-stacked bilayer graphene. The MT bilayer graphene is fabricated using a new transfer method that employs a micromechanical hemispherical handle substrate which allows defining small relative rotation angles (0.6$^{\circ}$ to 1.2$^{\circ}$ ) between two graphene flakes that stem from the same domain, with an accuracy of 0.1$^{\circ}$ . We observe the emergence of satellite transport gaps at $\pm$ 8 electrons per moir\'{e} unit cell, along with a conductivity minimum at charge neutrality. These features remain robust in the presence of a high transverse electric field, applied using dual gated device structures. In magnetic fields, we observe the emergence of a Hofstadter butterfly in the energy spectrum, with four-fold degenerate Landau levels, and broken symmetry QHS at $\nu \quad =$ $\pm$ 1, $\pm$ 2, $\pm$ 3.

*NRI-SWAN, Intel Corp, and National Science Foundation Grant No. EECS-1610008

Authors

  • kyounghwan kim

    • Univ of Texas, Austin
  • Ashley DaSilva

    • Department of Physics, University of Texas at Austin, Texas 78712, USA
    • Univ of Texas, Austin
  • Shengqiang Huang

    • University of Arizona
    • The University of Arizona
  • Babak Fallahazad

    • Univ of Texas, Austin
  • Stefano Larentis

    • Univ of Texas, Austin
  • Takashi Taniguchi

    • National Institute for Materials Science
  • Kenji Watanabe

    • National Institute for Materials Science
  • Brian J. LeRoy

    • University of Arizona
    • The University of Arizona
  • A. H. MacDonald

    • The University of Texas at Austin
    • Department of Physics, University of Texas at Austin, Texas 78712, USA
    • UT Austin
    • Univ of Texas, Austin
    • Department of Physics, University of Texas at Austin
    • Department of Physics, University of Texas at Austin, TX 78712, USA
  • Emanuel Tutuc

    • The University of Texas at Austin
    • Univ of Texas, Austin