Spin-charge Separated Solitons in a Topological Band Insulator

TL;DR

This paper introduces a two-dimensional topological insulator model that hosts spin-charge separated solitons linked to fluxes, offering new classification methods and insights into phase transitions involving emergent gauge fluxes.

Contribution

It presents a simple, controllable model demonstrating spin-charge separated solitons and proposes an alternative classification for $Z_2$ topological insulators without boundary analysis.

Findings

Discovery of spin-charge separated solitons associated with $\pi$ fluxes.

Proposed an alternative classification scheme for topological insulators.

Identified a phase transition triggered by soliton condensation into a ferromagnetic state.

Abstract

In this paper we construct a simple, controllable, two dimensional model based on a topological band insulator. It has many attractive properties. (1) We obtain spin-charge separated solitons that are associated with $\pi$ fluxes. (2) It suggests an alternative way to classify $Z_2$ topological band insulator without resorting to the sample boundary. (3) When the $\pi$ fluxes are dynamical variables, as in a correlated insulator with emergent gauge fluxes, these solitons are propagating bosonic excitations and their condensation triggers a phase transition into a planar ferromagnet.