paper

Monte Carlo Simulation of the Heisenberg Antiferromagnet on a Triangular Lattice: Topological Excitations

arXiv:cond-mat/9508128 · doi:10.1103/PhysRevB.52.13480

Abstract

We have simulated the classical Heisenberg antiferromagnet on a triangular lattice using a local Monte Carlo algorithm. The behavior of the correlation length , the susceptibility at the ordering wavevector , and the spin stiffness clearly reflects the existence of two temperature regimes -- a high temperature regime , in which the disordering effect of vortices is dominant, and a low temperature regime , where correlations are controlled by small amplitude spin fluctuations. As has previously been shown, in the last regime, the behavior of the above quantities agrees well with the predictions of a renormalization group treatment of the appropriate nonlinear sigma model. For , a satisfactory fit of the data is achieved, if the temperature dependence of and is assumed to be of the form predicted by the Kosterlitz--Thouless theory. Surprisingly, the crossover between the two regimes appears to happen in a very narrow temperature interval around .

13 pages, 8 Postscript figures

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