Excitations in one-dimensional S=1/2 quantum antiferromagnets

TL;DR

This paper investigates the nature of elementary excitations in one-dimensional S=1/2 quantum antiferromagnets, showing that triplons can serve as primary excitations even without fractionalization, challenging the necessity of spinons.

Contribution

It demonstrates that spectral weights are mainly in states with few triplets, suggesting triplons are sufficient as elementary excitations in these systems.

Findings

Spectral weight concentrates in few-triplon states

Triplons can replace spinons as elementary excitations

Fractional excitations are not necessary in low-dimensional antiferromagnets

Abstract

The transition from dimerized to uniform phases is studied in terms of spectral weights for spin chains using continuous unitary transformations (CUTs). The spectral weights in the S=1 channel are computed perturbatively around the limit of strong dimerization. We find that the spectral weight is concentrated mainly in the subspaces with a small number of elementary triplets (triplons), even for vanishing dimerization. So, besides spinons, triplons may be used as elementary excitations in spin chains. We conclude that there is no necessity to use fractional excitations in low-dimensional, undoped or doped quantum antiferromagnets.