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M Zannetti

Publications and source records attributed to M Zannetti.

At least 19 recordsLinked to original sources
PubMed2002

Off-equilibrium response function in the one-dimensional random-field Ising model.

A thorough numerical investigation of the slow dynamics in the d=1 random-field Ising model in the limit of an infinite ferromagnetic coupling is presented in this paper. Crossovers from the preasymptotic pure regime to the asymptotic Sinai regime are investigated for the average domain size, the autocorrelation function, and staggered magnetization. By switching on an additional small random field at the time t(w) the linear off-equilibrium response function is obtained, which displays as well the crossover from the nontrivial behavior of the d=1 pure Ising model to the asymptotic behavior where it vanishes identically.

Journal Article↗
PubMed2001

Interface fluctuations, bulk fluctuations, and dimensionality in the off-equilibrium response of coarsening systems.

The relationship between statics and dynamics proposed by Franz, Mezard, Parisi, and Peliti (FMPP) for slowly relaxing systems [Phys. Rev. Lett. 81, 1758 (1998)] is investigated in the framework of nondisordered coarsening systems. Separating the bulk from interface response we find that for statics to be retrievable from dynamics the interface contribution must be asymptotically negligible. How fast this happens depends on dimensionality. There exists a critical dimensionality above that the interface response vanishes like the interface density and below that it vanishes more slowly. At d=1 the interface response does not vanish leading to the violation of the FMPP scheme. This behavior is explained in terms of the competition between curvature-driven and field-driven interface motion.

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PubMed2000

Fluctuation dissipation ratio in the one-dimensional kinetic ising model

The exact relation between the response function R(t,t(')) and the two time correlation function C(t,t(')) is derived analytically in the one-dimensional kinetic Ising model subjected to a temperature quench. The fluctuation dissipation ratio X(t,t(')) is found to depend on time through C(t,t(')) in the time region where scaling C(t,t('))=f(t/t(')) holds. The crossover from the nontrivial form X[C(t,t('))] to X(t,t(')) identical with1 takes place as the waiting time t(w) is increased from below to above the equilibration time t(eq).

Journal Article↗