From general arguments, that are valid for spin models with sufficiently short-range interactions, we derive strong constraints on the excitation spectrum across a continuous phase transition at zero temperature between a magnetic and a dimerized phase, that breaks the translational symmetry. From the different symmetries of the two phases, it is possible to predict, at the quantum critical point, a branch of gapless excitations, not described by standard semiclassical approaches. By using these arguments, supported by intensive numerical calculations, we obtain a rather convincing evidence in favor of a first-order transition from the ferromagnetic to the dimerized phase in the two-dimensional spin-half model with a four-spin ring-exchange interaction, recently introduced by A.W. Sandvik, S. Daul, R.R.P. Singh, and D.J. Scalapino [Phys. Rev. Lett. 89, 247201 (2002)].

Theoretical constraints for the magnetic-dimer transition in two-dimensional spin models / Spanu, L; Becca, Federico; Sorella, Sandro. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 73:13(2006), pp. 134429.1-134429.7. [10.1103/PhysRevB.73.134429]

Theoretical constraints for the magnetic-dimer transition in two-dimensional spin models

Becca, Federico;Sorella, Sandro
2006-01-01

Abstract

From general arguments, that are valid for spin models with sufficiently short-range interactions, we derive strong constraints on the excitation spectrum across a continuous phase transition at zero temperature between a magnetic and a dimerized phase, that breaks the translational symmetry. From the different symmetries of the two phases, it is possible to predict, at the quantum critical point, a branch of gapless excitations, not described by standard semiclassical approaches. By using these arguments, supported by intensive numerical calculations, we obtain a rather convincing evidence in favor of a first-order transition from the ferromagnetic to the dimerized phase in the two-dimensional spin-half model with a four-spin ring-exchange interaction, recently introduced by A.W. Sandvik, S. Daul, R.R.P. Singh, and D.J. Scalapino [Phys. Rev. Lett. 89, 247201 (2002)].
2006
73
13
1
7
134429
http://link.aps.org/doi/10.1103/PhysRevB.73.134429
https://arxiv.org/abs/cond-mat/0512272
Spanu, L; Becca, Federico; Sorella, Sandro
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/13359
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