Ising model with competing next-nearest-neighbour interactions on the Kagome lattice

Abstract

Starting from a model for CsOH.H2O the authors investigate the phase diagram of a two-dimensional Ising model on the Kagome lattice with antiferromagnetic nearest-neighbour and competing ferromagnetic second- and third-nearest-neighbour interactions by Monte Carlo simulations. They obtain two Kosterlitz-Thouless transitions as in the six-state clock model and a crossover to second-order transitions where the critical exponents are consistent with those of the three-state Potts model. They also determine the ground state for all values of the coupling constants.