Topological hourglass Dirac semimetal in Ag<sub>2</sub>BiO<sub>3</sub>

ORAL

Abstract

Materials with tunable charge and lattice degrees of freedom provide excellent platforms for investigating multiple phases that can be controlled via external stimuli. We show how the charge-ordered ferroelectric oxide Ag2BiO3, which has been realized experimentally, presents a unique exemplar of a metal-insulator transition under an external electric field. Our first-principles calculations combined with a symmetry analysis, reveal the presence of a nearly ideal hourglass-Dirac-semimetal state in the nonpolar structure of Ag2BiO3. The low-energy band structure consists of two hourglass-like nodal lines located on two mutually orthogonal glide-mirror planes in the absence of spin-orbit coupling (SOC) effects. These lines cross at a common point and form an interlinked chain-like structure, which extends beyond the first Brillouin zone. Inclusion of the SOC opens a small gap in the nodal lines and results in two symmetry-enforced hourglass-like Dirac points on the C2y screw rotation axis. Our results indicate that Ag2BiO3 will provide an ideal platform for exploring ferroelectric-semiconductor to Dirac-semimetal transition by the application of an external electric field.

–

Presenters

  • Bahadur Singh

    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D
    • Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA /SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for
    • Department of Physics, National University of Singapore
    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science \& Technology, Engineering Technology Research Center for 2
    • Department of Physics, Northeastern University
    • Shenzhen University, Shenzhen, China
    • College of Optoelectronic Engineering, Shenzhen University

Authors

  • Bahadur Singh

    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D
    • Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA /SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for
    • Department of Physics, National University of Singapore
    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science \& Technology, Engineering Technology Research Center for 2
    • Department of Physics, Northeastern University
    • Shenzhen University, Shenzhen, China
    • College of Optoelectronic Engineering, Shenzhen University

  • Barun Ghosh

    • Physics, Indian Institute of Technology Kanpur,Kanpur 208016, India
    • Indian Institute of Technology Kanpur, India

  • Chenliang Su

    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D
    • SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science \& Technology, Engineering Technology Research Center for 2
    • Shenzhen University, Shenzhen, China
    • SZU-NUS Collaborative Center and International Collaborative, Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2

  • Hsin Lin

    • Academia Sinica
    • Institute of Physics, Academia Sinica
    • Physics, Academia Sinica, Taipei 11529, Taiwan
    • Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
    • Physics, Academia Sinica
    • Department of Physics, National University of Singapore
    • National University of Singapore
    • Academia Sinica, Taipei, Taiwan

  • Amit Agarwal

    • Physics, Indian Institute of Technology Kanpur,Kanpur 208016, India
    • Indian Institute of Technology Kanpur, India

  • Arun Bansil

    • Department of Physics, Northeastern University
    • Northeastern
    • Physics, Northeastern University, Boston, Massachusetts 02115, USA
    • Northeastern University
    • Northeastern University, Boston (MA), USA
    • Physics, Northeastern U.
    • Department of Physics, Northwestern University
    • Physics, Northeastern University, Boston, MA, USA