Effective spin models for spin-phonon chains by flow equations

Citation
C. Raas et al., Effective spin models for spin-phonon chains by flow equations, EUR PHY J B, 21(3), 2001, pp. 369-374
Citations number
23
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
EUROPEAN PHYSICAL JOURNAL B
ISSN journal
14346028 → ACNP
Volume
21
Issue
3
Year of publication
2001
Pages
369 - 374
Database
ISI
SICI code
1434-6028(200106)21:3<369:ESMFSC>2.0.ZU;2-9
Abstract
We investigate the anti-adiabatic limit of an anti-ferromagnetic S = 1/2 He isenberg chain coupled to Einstein phonons. The flow equation method is use d to decouple the spin and the phonon part of the Hamiltonian. In the effec tive spin model long range spin-spin interactions are generated. We determi ne the phase transition from a gapless state to a gapped (dimerized) phase, which occurs at a non-zero value of the spin-phonon coupling. In the effec tive phonon sector a phonon hardening is observed.