Emergent Edge Modes in Shifted Quasi-One-Dimensional Charge Density Waves

Song-Bo Zhang, Xiaoxiong Liu, Md Shafayat Hossain, Jia-Xin Yin, M. Zahid Hasan, and Titus Neupert

Phys. Rev. Lett. 130, 106203 – Published 8 March 2023

Abstract

We propose and study a two-dimensional phase of shifted charge density waves (CDW), which is constructed from an array of weakly coupled 1D CDW wires whose phases shift from one wire to the next. We show that the fully gapped bulk CDW has topological properties, characterized by a nonzero Chern number, that imply edge modes within the bulk gap. Remarkably, these edge modes exhibit spectral pseudoflow as a function of position along the edge, and are thus dual to the chiral edge modes of Chern insulators with their spectral flow in momentum space. Furthermore, we show that the CDW edge modes are stable against interwire coupling. Our predictions can be tested experimentally in quasi-1D CDW compounds such as ${Ta}_{2} {Se}_{8} I$ .

Received 12 April 2022
Revised 5 November 2022
Accepted 10 February 2023

DOI:https://doi.org/10.1103/PhysRevLett.130.106203

Physics Subject Headings (PhySH)

Charge density waves Edge states

Topological materials

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Song-Bo Zhang ^1,*, Xiaoxiong Liu¹, Md Shafayat Hossain², Jia-Xin Yin³, M. Zahid Hasan^2,4,5,6, and Titus Neupert ^1,†

¹Department of Physics, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
²Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08540, USA
³Department of physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
⁴Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08540, USA
⁵Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁶Quantum Science Center, Oak Ridge, Tennessee 37831, USA