Publication : t95/149

Generalized helimagnets between two and four dimensions

David F. (CEA, DSM, SPhT (Service de Physique Théorique), F-91191 Gif-sur-Yvette, FRANCE)
Jolicoeur T. (CEA, DSM, SPhT (Service de Physique Théorique), F-91191 Gif-sur-Yvette, FRANCE)
We study the phase transitions of N-components generalized helimagnets that obey the symmetry breaking pattern ${\rm O}(N)\times {\rm O}(N-1)\rightarrow {\rm O}(N-1)_{\rm diag}$. In the neighborhood of two dimensions, a $D=2+\epsilon$ renormalization group study reveals a rich fixed point structure as well as a nematic-like phase with partial spin ordering. In the physical case ${\rm O}(3)\times {\rm O}(2)\rightarrow {\rm O}(2)_{\rm diag}$, relevant to real magnets with noncollinear ordering, we show that this implies an XY-like transition between the ordered phase and the nematic-like phase. A non-Abelian mean-field calculation qualitatively valid above four dimensions is shown to lead to the same picture but then the principal chiral fixed point, which had been proposed earlier as the relevant fixed point for D=3 helimagnets, plays no role due to the appearance of a first-order line.
Année de publication : 1996
Revue : Phys. Rev. Lett. 76 3148-3151 (1996)
DOI : 10.1103/PhysRevLett.76.3148
Preprint : arXiv:cond-mat/9512147
Lien :
Langue : Anglais

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