Effects of quenched disorder in the two-dimensional potts model: A monte carlo study

Abstract:

Motivated by recent experiments on phase behavior of systems confined in porous media, we have studied the effect of randomness on the nature of the phase transition in the two-dimensional Potts model. To model the effects of the porous matrix we introduce a random distribution of couplings [Formula Presented] in the q state Potts Hamiltonian. An extensive Monte Carlo study is made on this system for [Formula Presented]. We studied two different cases of disorder (a) [Formula Presented] and [Formula Presented] and (b) [Formula Presented] and [Formula Presented]. We observed, in both cases, that the weak first order transition that appears in the pure case, changes to a second-order transition. A finite size scaling analysis shows that the correlation length exponent [Formula Presented] is close to [Formula Presented] and the best fit to the dependence of the specific heat on system size is logarithmic. This suggests that both cases belong to the universality class of the Ising model. In contrast, the magnetic exponents point to a different universality class. © 1999 The American Physical Society.

Año de publicación:

1999

Keywords:

Fuente:

scopus