Papers by Keyword: Diluted Systems

Abstract: In the past few years, systems with slow dynamics have attracted considerable interest. Coarsening effects are exhibited in a wide range of systems. Non-equilibrium critical behavior of 2D XY-model demonstrates slow dynamics in a wide temperature range. The coarsening in pure and diluted 2D XY-model are investigated for various defects concentration. The period of logarithmic grows of cluster size was found.

Abstract: Renormalization-group approach is applied to investigate the short-time nonequilibriumcritical behavior of pure and diluted spin systems with nonmagnetic point-like impurities.The dissipative relaxation dynamics with non-conserved order parameter is considered. For thefirst time the description of the order parameter growth induced by the initial nonequilibriumstate of system is carried out at fixed dimension d = 3 without use of ε-expansion.

Abstract: The phase transitions and critical phenomena in three-dimensional (3D) site-diluted 3-and 4-state Potts models is investigated by Monte-Carlo method based on the highly efficient Wolff algorithm. The systems with linear sizes L=20-44 at spin concentrations p=1.00, 0.95, 0.90, 0.80, 0.70, 0.65 are explored. The second-order phase transition is shown to occur in the three-dimensional 3-state Potts model with nonmagnetic impurities. In the 4-state Potts model there are observed first-order phase transitions in weakly diluted state, when the model is strongly diluted the first-order phase transitions change to the second-order one. On the basis of the finite-size scaling theory static critical exponents of specific heat α, susceptibility γ , magnetization β, and exponent of correlation radius ν for the systems under study are calculated.