Topological phase transition between a normal insulator and a topological metal state in a quasi-one-dimensional system

Milad Jangjan,Mir Vahid Hosseini

doi:10.1038/s41598-021-92390-x

Abstract

We theoretically report the finding of a new kind of topological phase transition between a normal insulator and a topological metal state where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. Such states living on a quasi-one-dimensional system with three sublattices per unit cell are protected by hidden inversion symmetry. While other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.

Highlights

In order to identify the localized edge states penetrated into extended bulk states under open boundary conditions, in the following, we evaluate the inverse participation ratio (IPR) of states[25]
We introduced a quasi-1D model that presents a new topological phase transition between the topological metals (TMs) phase and normal insulator (NI)
The Hamiltonian of system can be block-diagonalized into two subsystems in the presence of exchange symmetry

Summary

Introduction

The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. In such phase transition, in addition to gap closing-reopening between two bands, another band passes the Fermi level (Fig. 2) resulting in the emergence of zero-energy edge states within bulk states (Fig. 3a).

Results

Conclusion