Tricritical universality in a two-dimensional spin fluid

Monte Carlo simulations are used to investigate the tricritical point properties of a two-dimensional (2D) spin fluid. Measurements of the scaling operator distributions are employed in conjunction with a finite-size scaling analaysis to locate the tricritical point and determine the directions of the relevant scaling fields and their associated tricritical exponents. The scaling operator distributions and exponents are shown to match quantitatively those of the 2D Blume-Capel model, confirming that both models belong to the same universality class. Mean-field calculations of the tricritical point location are also compared with the simulation measurements. \textcopyright{} 1996 The American Physical Society.