Structure of domain walls in chiral spin liquids

TL;DR

This paper investigates the structure and properties of domain walls in chiral spin liquids, revealing gapless edge modes, non-universal domain wall characteristics, and non-analytic contributions to the domain wall theory.

Contribution

It provides a self-consistent mean-field and Ginzburg--Landau framework for understanding domain walls in chiral spin liquids, including novel non-analytic effects.

Findings

Existence of gapless edge modes at domain walls.

Non-universal domain wall width and tension.

Identification of a non-analytic || term in the domain wall theory.

Abstract

The chiral spin liquid is one of the canonical examples of a topological state of quantum spins coexisting with symmetry-breaking chiral order; its experimental realization has been actively discussed in the past few years. Here, motivated by the interplay between topology and symmetry breaking, we examine the physics of the interface between two chiral spin liquid domains with opposite chiralities. We show that a self-consistent mean-field description for the spinons exists that describes both the change of chirality at the domain wall and the gapless edge modes living on it. A Ginzburg--Landau theory for the domain wall is formulated based on the mean-field picture, from which we obtain the non-universal properties of the domain wall such as the wall width and tension. We show that the velocity of the topologically protected domain wall edge states can be accessed through the Jackiw-Rebbi mechanism. We further argue that the gapless modes at the edge contribute an extra, non-analytic $|\phi^3|$ term to the domain wall theory, and find numerical evidence for this non-analyticity.