MAGNETIC PHASE-DIAGRAM OF THE FERROMAGNETICALLY STACKED TRIANGULAR XYANTIFERROMAGNET - A FINITE-SIZE-SCALING STUDY

Histogram Monte Carlo simulation results are presented for the magneti c-field-temperature phase diagram of the XY model on a stacked triangu lar lattice with antiferromagnetic intraplane and ferromagnetic interp lane interactions. Finite-size scaling results at the various transiti on boundaries are consistent with expectations based on symmetry argum ents. Although a molecular-field treatment of the Hamiltonian fails to reproduce the correct structure for the phase diagram, it is demonstr ated that a phenomenological Landau-type free-energy model contains al l the essential features. These results serve to complement and extend our earlier work [Phys. Rev. B 48, 3840 (1993)].