XY-Nature of the Fully Frustrated Ising Model on the Triangular Lattice

抄録

The XY-nature of the Ising model on the triangular lattice with the antiferromagnetic nn and ferromagnetic nnn interactions is studied by Monte Carlo simulations. The order parameter is defined via the cell spin which represents a set of Ising variables in each frustrated unit cell. The finite size effects on the xy- and z-components of the order parameter are analyzed separately. The fluctuation of the absolute value of the order parameters is introduced as a generalized susceptibility. The successive phase transition feature with the Kosterlitz-Thouless-like phase is strongly confirmed. A non-universal character of the model is discussed.