Bound-states in dimerized and frustrated Heisenberg Chains

TL;DR

This paper uses the Bond Operator Technique to analyze low-energy excitations in a frustrated dimerized antiferromagnetic Heisenberg chain, revealing bound states of elementary triplets and comparing well with exact diagonalization data.

Contribution

It provides a new analytical approach to identify bound states in frustrated dimerized chains, showing good agreement with numerical methods.

Findings

Only one elementary excitation branch identified.

Bound states of two triplets exist below the continuum.

Qualitative and quantitative agreement with ED data.

Abstract

Using the Bond Operator Technique (BOT), we have studied the low energy excitationspectrum of a frustrated dimerized antiferromagnetic Heisenberg chain. In particular, we have compared our analytical results with previous Exact Diagonalizations (ED) data. Qualitatively, the BOT results are in good agreement with the ED data. And even a very good quantitative agreement is obtained in some parameter region. It is clearly shown that there is only one elementary excitation branch (lowest triplet branch) and that the two other well defined excitations which appear below the continuum, one singlet and one triplet, are bound states of two elementary triplets.