Helimagnetism in XY models: Domain walls, frustrations, fractional vortices, and phase transitions

Gennadi Uimin, Alberto Pimpinelli

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

We consider in this paper a model for two-dimensional XY helimagnets, which was proposed in Pimpinelli et al. [J. Phys. Condens. Matter 3, 4693 (1991)]. In this model the usual spin waves and vortices coexist with chirality degrees of freedom in such a way that the degeneracy space of the order parameter is O(2)×Z2. In Pimpinelli et al. the low-temperature behavior of the model was addressed, and an infinite sequence of first-order phase transitions was shown to take place, due to the spin-wave coupling between domains with opposite chirality. Here we investigate the same model at higher temperatures, where vortices in the spin system and kinks on domain walls are thermally excited. The kinks in domain walls are associated with noninteger (fractional) vortices. This is presumably a common feature also in conventional helimagnets, where the Z2 chirality is due to the twofold handedness of helices. We also discuss the applicability of this scenario to the helimagnetic compound BaCo2(AsO4)2.

Original languageEnglish (US)
Pages (from-to)1123-1135
Number of pages13
JournalPhysical Review E
Volume49
Issue number2
DOIs
StatePublished - 1994

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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