Spectrum of elementary and collective excitations in the dimerized S=1/2 Heisenberg chain with frustration

P. V. Shevchenko*, V. N. Kotov, O. P. Sushkov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

We have studied the low-energy excitation spectrum of a dimerized and frustrated antiferromagnetic Heisenberg chain. We use an analytic approach, based on a description of the excitations as triplets above a strong-coupling singlet ground state. The quasiparticle spectrum is calculated by treating the excitations as a dilute Bose gas with infinite on-site repulsion. Additional singlet (S=0) and triplet (S=1) modes are found as two-particle bound states of the elementary triplets. We have also calculated the contributions of the elementary and collective excitations into the spin structure factor. Our results are in excellent agreement with exact diagonalizations and dimer series expansions data as long as the dimerization parameter δ is not too small (δ>0.1), i.e., while the elementary triplets can be treated as localized objects.

Original languageEnglish
Pages (from-to)3305-3315
Number of pages11
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume60
Issue number5
Publication statusPublished - 1 Aug 1999
Externally publishedYes

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