Imaging a nematic electronic domain wall and its edge modes on the surface of bismuth

ORAL

Abstract

Nematic electronic phases, whose wave functions spontaneously break the rotational symmetry of the underlying lattice, are susceptible to the formation of domains. In this talk, I will describe scanning tunneling microscope measurements that allow us to directly visualize the evolution of local nematic order across a domain wall on the surface of bismuth. Coulomb interactions in this material lift the degeneracy of six anisotropic hole valleys to produce nematic quantum Hall states [1]. Spatially resolved spectroscopy shows that the resulting exchange gap between Landau levels closes in the vicinity of the domain wall, where there is an abrupt switch in which valleys are occupied, as seen by imaging the orientation of anisotropic wave functions on either side. The data match well to theoretical simulations where the boundary is predicted to support counter-propagating valley-polarized edge modes, forming an extended topological defect. While we observe enhanced low-energy conductance at the boundary, atomic-scale defects allow for scattering between valleys that partially localizes the one-dimensional electronic states.

[1] B. E. Feldman et al., Science, 354, 316 (2016).

*We acknowledge funding from the Moore Foundation, DOE, NSF-DMR, and NSF-MRSEC.

–

Presenters

  • Benjamin Feldman

    • Joseph Henry Laboratories & Department of Physics, Princeton University
    • Princeton University

Authors

  • Benjamin Feldman

    • Joseph Henry Laboratories & Department of Physics, Princeton University
    • Princeton University

  • Mallika Randeria

    • Joseph Henry Laboratories & Department of Physics, Princeton University
    • Princeton University

  • Hao Ding

    • Joseph Henry Laboratories & Department of Physics, Princeton University
    • Princeton University

  • Kartiek Agarwal

    • Departments of Electrical Engineering and Physics, Princeton University
    • Princeton University
    • Department of Electrical Engineering, Princeton University
    • Electrical Engineering, Princeton Univ

  • Huiwen Ji

    • Department of Chemistry, Princeton University
    • Princeton University

  • Robert Cava

    • Department of Chemistry, Princeton University
    • Princeton
    • Princeton University
    • Chemistry, Princeton Univ
    • Princeton Univ

  • Siddharth Parameswaran

    • Rudolf Peierls Center for Theoretical Physics, University of Oxford
    • The Rudolph Peierls Centre for Theoretical Physics, University of Oxford

  • Shivaji Sondhi

    • Departments of Electrical Engineering and Physics, Princeton University
    • Department of Physics, Princeton University

  • Ali Yazdani

    • Physics department, Princeton Univ
    • Joseph Henry Laboratories & Department of Physics, Princeton University
    • Physics Department, Princeton University
    • Physics, Princeton University
    • Princeton University