Electron Collimation in Twisted Bilayer Graphene via Gate-Defined Moiré Barriers

ORAL

Abstract

Electron collimation via a graphene p−n junction allows electrostatic control of ballistic electron trajectories akin to that of an optical circuit. Similar manipulation of novel correlated electronic phases in twisted-bilayer graphene (tBLG) can provide additional probes to the underlying physics and device component toward advanced quantum electronics. In this work, we demonstrate collimation of the electron flow via gate-defined moiré barriers in a tBLG device, utilizing the band-insulator gap of the moiré superlattice. A single junction can be tuned to host a chosen combination of conventional pseudo barrier and moiré tunnel barriers, from which we demonstrate improved collimation efficiency. By measuring transport through two consecutive moiré collimators separated by 1 μm, we demonstrate evidence of electron collimation in tBLG in the presence of realistic twist-angle inhomogeneity.

**This work is supported by the National Science Foundation CAREER Award NSF-1944498 and the National Science Foundation DMREF Award DMR-1922165. Nanofabrication is conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network, Award Number NNCI-1542202.

–

Publication: W. Ren, X. Zhang, Z. Zhu, M. Khan, K. Watanabe, T. Taniguchi, E. Kaxiras, M. Luskin, and K. Wang, Electron Collimation in Twisted Bilayer Graphene via Gate-Defined Moiré Barriers, Nano Lett. 24, 12508 (2024).

Presenters

  • Wei Ren

    • University of Minnesota

Authors

  • Wei Ren

    • University of Minnesota

  • Xi Zhang

    • University of Minnesota
    • Georgia Institute of Technology

  • Ziyan Zhu

    • Stanford University

  • Moosa A Khan

    • University of Minnesota

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • Research Center for Functional Materials, National Institute for Materials Science
    • Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • Research Center for Functional Materials, National Institute of Material Science, Tsukuba, Japan
    • National Institute of Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science

  • Takashi Taniguchi

    • National Institute for Materials Science
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute of Material Science, Tsukuba, Japan
    • Advanced Materials Laboratory, National Institute for Materials Science

  • Efthimios Kaxiras

    • Harvard University

  • Mitchell Luskin

    • University of Minnesota

  • Ke Wang

    • University of Minnesota