A Renormalization Group Study of Helimagnets in D=2+EPSILON Dimensions

Дата и время публикации : 1993-04-30T17:35:00Z

Авторы публикации и институты :
P. Azaria
B. Delamotte
F. Delduc
Th. Jolicoeur

Ссылка на журнал-издание: Nuclear Physics B408[FS], 485 (1993)
Коментарии к cтатье: 25 pages and 1 figure not included, LateX, Saclay preprint SPhT/93-044
Первичная категория: cond-mat

Все категории : cond-mat

Краткий обзор статьи: We study a non linear sigma model $O(N)otimes O(2)/O(N-2)otimes O(2)$ describing the phase transition of N-components helimagnets up to two loop order in $D=2+epsilon$ dimensions. It is shown that a stable fixed point exists as soon as $N$ is greater than 3 (or equal). In the N=3 case, the symmetry of the system is dynamically enlarged at the fixed point to O(4) We show that the order parameter for Heisenberg helimagnets involves a tensor representation of $O(4)$. We show that for large $N$ and in the neighborhood of two dimensions this nonlinear sigma model describes the same critical theory as the Landau-Ginzburg linear theory. We deduce that there exists a dividing line $N_c (D)$ in the plane $(N, D)$ separating a first-order region containing the Heisenberg point at $D=4$ and a second-order region containing the whole $D=2$ axis. We conclude that the phase transition of Heisenberg helimagnets in dimension 3 is either first order or second order with $O(4)$ exponents involving a tensor representation or tricritical.

Category: Physics