Finite-Size Scaling Study of the Three-State Potts Model in Random Fields: Evidence for a Second-Order Transition

1995 ◽  
Vol 30 (6) ◽  
pp. 331-336 ◽  
Author(s):  
K Eichhorn ◽  
K Binder
1996 ◽  
Vol 463 ◽  
Author(s):  
R. Paredes ◽  
J. Valbuena

ABSTRACTMotivated by recent experiments on phase behavior of systems confined in porous media, we have studied the effect of quenched bond randomness on the nature of the phase transition in the two dimensional Potts model. To model the effects of the porous matrix we chose the couplings of the q state Potts Hamiltonian from the distribution P(Jij) = pδ(Jij – J) + (1 – p)δ(Jij). For a range of p values, away from the percolation threshold, the transition temperature follows the mean field prediction Tc(p) = Tc(1)p. Furthermore, we observed that the strong first order transition, that appears in the pure case for q = 10, changes two a second order transition. It is also clear from our simulations that the second order transition of the q = 3 pure case changes to a second order transition of a different universality class. A finite size scaling analysis suggests that in both cases the critical exponents, in the presence of disorder, fall into the universality class of the two dimensional pure Ising model. This result agrees with theoretical calculations recently published [1].


1990 ◽  
Vol 59 (5-6) ◽  
pp. 1397-1429 ◽  
Author(s):  
M. Fukugita ◽  
H. Mino ◽  
M. Okawa ◽  
A. Ukawa

2019 ◽  
Vol 2019 (9) ◽  
Author(s):  
Kimihiko Fukushima ◽  
Kazumitsu Sakai

Abstract A crossing probability for the critical four-state Potts model on an $L\times M$ rectangle on a square lattice is numerically studied. The crossing probability here denotes the probability that spin clusters cross from one side of the boundary to the other. First, by employing a Monte Carlo method, we calculate the fractal dimension of a spin cluster interface with a fluctuating boundary condition. By comparison of the fractal dimension with that of the Schramm–Loewner evolution (SLE), we numerically confirm that the interface can be described by the SLE with $\kappa=4$, as predicted in the scaling limit. Then, we compute the crossing probability of this spin cluster interface for various system sizes and aspect ratios. Furthermore, comparing with the analytical results for the scaling limit, which have been previously obtained by a combination of the SLE and conformal field theory, we numerically find that the crossing probability exhibits a logarithmic correction ${\sim} 1/\log(L M)$ to the finite-size scaling.


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