Phase transition of ising spin glass models in two dimensions

We examine the phase transition of Ising spin glass models in two dimension s (2D), calculating complementary two quantities, i.e., the interface free energy <(Delta F(T))over bar> and the Binder parameter g(L), on finite L x L (L less than or equal to 24) lattices at very low temperatures T. We find that these quantities exhibit quite different features depending on the di stribution of bonds. For the +/-J distribution, <(Delta F(T))over bar> at v ery low temperatures slightly increases with L and g(L) intersect at T simi lar to 0.25J. These results suggest a non-zero temperature phase transition , Tc not equal 0. On the other hand, for the Gaussian distribution, <(Delta F(T))over bar> decreases as L increases even at T = 0 and g(L) for differe nt L converges to unity at T = 0. These results confirm the assumption of t he zero temperature phase transition, T-c = 0. Finite-size scaling analyses support those results. Thus we suggest that, in 2D, the existence of a fin ite-temperature phase transition depends on the distribution of bonds and i t exists when the bond distribution is +/-J.