Coarsening Dynamics of Coulomb Glass Model

Abstract

In this talk, I present numerical results from a comprehensive Monte Carlo study in two dimensions of coarsening kinetics in the Coulomb glass (CG) model on a square lattice. The CG model is characterized by spin-spin interactions which are long-range Coulombic and antiferromagnetic. For the nonequilibrium properties we have studied spatial correlation functions and domain growth laws. At half filling and small disorders, we find that domain growth in the CG is analogous to that in the nearest-neighbor random-field Ising model. The domain length scale L(t ) shows a crossover from a regime of “power-law growth with a disorder-dependent exponent” [L(t ) ∼ t 1/z̄ ] to a regime of “logarithmic growth with a universal exponent” [L(t ) ∼ (ln t ) 1/ψ ]. We next look at the results for the asymmetric CG (slightly away from half filling) at zero disorder, where the ground state is checkerboard-like with excess holes distributed uniformly. We find that the evolution morphology is in the same dynamical universality class as the ordering ferromagnet. Further, the domain growth law is slightly slower than the Lifshitz-Cahn-Allen law, L(t ) ∼ t 1/2 , i.e., the growth exponent is underestimated. We speculate that this could be a signature of logarithmic growth in the asymptotic regime.