Monte Carlo study of the phase diagram of layered XY antiferromagnet

Abstract

The three dimensional XY model is considered in the presence of uniform magnetic field applied in the X-direction. The nearest neighbour intraplanar interaction is considered ferromagnetic and the interplanar nearest neighbour interaction is considered antiferromagnetic. Starting from high temperature initial random spin configuration the equilibrium phase of the system at any finite temperature was achieved by cooling the system using Monte Carlo single spin flip Metropolis algorithm with random updating rule. The components of total magnetisation and the sublattice magnetisations were calculated. The variance of antiferromagnetic order parameter and the specific heat were calculated. In a specific range of relative strengths of interactions (antiferromagnetic/ferromagnetic), the system shows multiple equilibrium phase transitions as observed from the double peaks of the specific heat plotted against the temperature. The phase diagrams (in the field-temperature plane) were obtained for different relative interaction strength. The two boundaries meet at some bicritical point. The bicritical point was found to move towards higher values of temperature and field as the strength of relative interaction increases.