Solitonic excitations in the Haldane phase of a S=1 chain

TL;DR

This paper investigates the nature of low-energy excitations in the Haldane phase of a one-dimensional S=1 antiferromagnetic chain, revealing that the fundamental excitations are solitonic in nature, specifically moving hidden domain walls.

Contribution

It demonstrates that the lowest excitations in the S=1 chain are solitonic, modeled as moving hidden domain walls, providing insight into the excitation spectrum of the Haldane phase.

Findings

Lowest excitations form a discrete triplet branch

Excitations can be modeled by approximate wave functions

Wave functions correspond to moving hidden domain walls

Abstract

We study low-lying excitations in the 1D $S=1$ antiferromagnetic valence-bond-solid (VBS) model. In a numerical calculation on finite systems the lowest excitations are found to form a discrete triplet branch, separated from the higher-lying continuum. The dispersion of these triplet excitations can be satisfactorily reproduced by assuming approximate wave functions. These wave functions are shown to correspond to moving hidden domain walls, i.e. to one-soliton excitations.