Electric Field Tuned Quantum Phase Transition from Conventional to Topological Insulator in Few-Layer Na3Bi

ORAL

Abstract

Na3Bi in bulk form represents a zero-bandgap topological Dirac semimetal (TDS), but when confined to few-layers it is predicted that a non-zero bandgap can be opened that in monolayer Na3Bi is ~300 meV.1 Application of an electric field to few-layer Na3Bi has been predicted to induce a topological phase transition from conventional to topological insulator.2 However, opening a bandgap in TDS has proven elusive, as efforts to grow thin films have only succeeded in growing 15-20 nm films that remain zero-bandgap semimetals. Here we demonstrate the growth of epitaxial few-layer Na3Bi via MBE, and probe its electronic structure and response to an electric field using scanning probe microscopy/spectroscopy and angle-resolved photoelectron spectroscopy. We demonstrate a bandgap >400 meV in ultrathin Na3Bi. Furthermore, via application of an electric field the bandgap can be tuned to semi-metallic and then re-opened (presumably in the quantum spin Hall phase) to greater than 100 meV. The electric fields required to induce this transition are below the breakdown field of many conventional dielectrics, making the creation of a topological transistor based on a few-layer TDS within reach.
1 C. Niu, et al., Phys. Rev. B 95, 075404 (2017)
2 H. Pan, et al., Scientific Reports 5, 14639 (2015)

–

Presenters

  • Mark Edmonds

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University

Authors

  • Mark Edmonds

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University

  • James Collins

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University

  • Anton Tadich

    Australian Synchrotron

  • Lidia Gomes

    Department of Physics and Centre for Advanced 2D Materials, National University of Singapore

  • João Rodrigues

    National University of Singapore, Department of Physics and Centre for Advanced 2D Materials, National University of Singapore

  • John Hellerstedt

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University, School of Physics and Astronomy, Monash University, Czech Academy of Sciences Institute of Physics

  • Chang Liu

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University

  • Hyejin Ryu

    Lawrence Berkeley National Lab, Lawrence Berkeley National Laboratory, Lawrence Berkeley Natl Lab

  • Shujie Tang

    Stanford University, Lawrence Berkeley National Laboratory, SIMIS, Stanford University

  • Weikang Wu

    Singapore University of Technology and Design

  • Shengyuan Yang

    Singapore University of Technology and Design, Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore U. of Tec. and Design, Engineering Product Development Pillar, Singapore University of Technology and Design

  • Shaffique Adam

    Centre for Advanced 2D Materials, National University of Singapore, Yale-NUS College, Department of Physics and Centre for Advanced 2D Materials, National University of Singapore, Yale-NUS College and Natl Univ of Singapore

  • Sung-Kwan Mo

    Lawrence Berkeley National Lab, Lawrence Berkeley Natl Lab, Lawrence Berkeley National Laboratory, Pohang Accelerator Laboratory, Advanced Light Source, Lawrence Berkeley National Laboratory

  • Michael Fuhrer

    Department of Physics and Astronomy and Centre for Future Low Energy Electronics Technologies, Monash University, ARC Centre of Excellence in Future Low-Energy Electronics Technologies (fleet.org.au), Monash University, Monash Center for Atomically Thin Materials, Monash University