Phase transitions in staggered spin ladders

We map spin ladders with nl legs and couplings J' across all rungs and 7(1 ± γ) along the legs, staggered in both directions, to a sigma model. Setting its θ = (2m + 1)π (where it is known to be gapless), we locate the critical curves in the γ versus J'/J plane at each nl, and spin S. The...

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Detalhes bibliográficos
Autores: Martín-Delgado, Miguel Ángel, Shankar, R., Sierra, Germán
Formato: artículo
Fecha de publicación:1996
País:España
Recursos:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/102696
Acesso em linha:http://hdl.handle.net/10261/102696
Access Level:acceso abierto
Palavra-chave:[PACS] Quantized spin models
[PACS] Antiferromagnetics
[PACS] Spin waves
Descrição
Resumo:We map spin ladders with nl legs and couplings J' across all rungs and 7(1 ± γ) along the legs, staggered in both directions, to a sigma model. Setting its θ = (2m + 1)π (where it is known to be gapless), we locate the critical curves in the γ versus J'/J plane at each nl, and spin S. The phase diagram is rich and has some surprises: When two gapped chains are suitably coupled, the combination becomes gapless. With nl, γ, and J'/J to control, the prospects for experimentally observing any one of these equivalent transitions are enhanced. We interpret our results in the framework of the resonating valence bond description of ladders. © 1996 The American Physical Society