Nonequilibriun Critical Dynamics and Correlations for the Ising Model Embedded in Fractal Structures

BAB, MARISA ALEJANDRA; FABRICIUS, GABRIEL; ALBANO, EZEQUIEL

Bariloche, Argentina

Workshop; IX LATIN AMERICAN WORKSHOP ON NONLINEAR PHENOMENA- LAWNP2005; 2005

Instituto Balseiro

We have investigated the nonequilibrium critical dynamics of a two dimensional Ising model embedded in infinitely ramified fractal structures, represented by Sierpinsky Carpets, with Hausdorff dimensions 1,8927, 1,7925 and 1,7227. The evolution of the systems are followed, at criticality, after annealing complete ordered spin configurations (ground state) and after quenching fully disordered initial configurations (high temperature state), by means of Monte Carlo simulations. From the power-law behavior of physical observables measured during the short-time regime of the dynamics, the complete set of critical exponents characteristic of the second-order phase transitions exhibited by the ising magnet on each fractal, were evaluated. Also, the dynamic exponents of the critical initial increase of the magnetization, as well as the critical temperature, were evaluated. The obtained values are independent of the initial states, but show a convergent trend with the fractal generation (size of the system). Logarithmic-periodic oscillatory corrections to the power law of the magnetization were observed, that may be a result from the discrete scale invariance of the fractal structure. On the other hand, the study of the equal-time two-spin correlation functions indicate a breakdown of the standard non-equilibrium dynamics scaling, when the systems were quenched from the high temperature state to criticality. Presentación: Poster