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Finite-temperature ordering in a two-dimensional highly frustrated spin model

A. Honecker·D. C. Cabra·H. -U. Everts·P. Pujol·F. Stauffer
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Abstract

We investigate the classical counterpart of an effective Hamiltonian for a strongly trimerized kagome lattice. Although the Hamiltonian only has a discrete symmetry, the classical groundstate manifold has a continuous global rotational symmetry. Two cases should be distinguished for the sign of the exchange constant. In one case, the groundstate has a 120^\circ spin structure. To determine the transition temperature, we perform Monte-Carlo simulations and measure specific heat, the order parameter as well as the associated Binder cumulant. In the other case, the classical groundstates are macroscopically degenerate. A thermal order-by-disorder mechanism is predicted to select another 120^\circ spin-structure. A finite but very small transition temperature is detected by Monte-Carlo simulations using the exchange method.

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A. Honecker, D. C. Cabra, H. -U. Everts, P. Pujol, F. Stauffer. 2006-09-13. Finite-temperature ordering in a two-dimensional highly frustrated spin model. https://doi.org/10.1088/0953-8984%2F19%2F14%2F145249

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