Softening of first-order transition in three-dimensions by quenched disorder - art. no. 036120

We study by extensive Monte Carlo simulations the effect of random bond dil ution on the phase transition of (lie three-dimensional four-state Potts mo del that is known to exhibit a strong first-order transition in the pure ca se. The phase diagram in the dilution-temperature plane is determined from the peaks of the susceptibility for sufficiently large system sizes. In the strongly disordered regime, numerical evidence for softening to a second-o rder transition induced by randomness is given. Here a large-scale finite-s ize scaling analysis, made difficult due to strong crossover effects presum ably caused by the percolation fixed point, is performed.