HISTOGRAM MONTE-CARLO STUDY OF THE NEXT-NEAREST-NEIGHBOR ISING ANTIFERROMAGNET ON A STACKED TRIANGULAR LATTICE

Critical properties of the Ising model on a stacked triangular lattice , with antiferromagnetic first- and second-neighbor in-plane interacti ons, are studied by extensive histogram Monte Carlo simulations. The r esults, in conjunction with the recently determined phase diagram, str ongly suggest that the transition from the period-3 ordered state to t he paramagnetic phase remains in the XY universality class. This concl usion is in contrast with a previous suggestion of mean-field tricriti cal behavior.