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Violation of the Fluctuation-Dissipation Theorem in a Two-Dimensional Ising Model with Dipolar Interactions

Daniel A. Stariolo·Sergio A. Cannas
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Abstract

The violation of the Fluctuation-Dissipation Theorem (FDT) in a two-dimensional Ising model with both ferromagnetic exchange and antiferromagnetic dipolar interactions is established and investigated via Monte Carlo simulations. Through the computation of the autocorrelation C(t+t_w,t_w) and the integrated response (susceptibility) functions we obtain the FDT violation factor X(t+t_w,t_w) for different values of the temperature, the waiting time t_w and the quotient delta=J_0/J_d, J_0 and J_d being the strength of exchange and dipolar interactions respectively. For positive values of delta this system develops a striped phase at low temperatures, in which the non-equilibrium dynamics presents two different regimes. Our results show that such different regimes are not reflected in the FDT violation factor, where X goes always to zero for high values of t_w in the aging regime, a result that appears in domain growth processes in non-frustrated ordered systems.

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Daniel A. Stariolo, Sergio A. Cannas. 1999-03-08. Violation of the Fluctuation-Dissipation Theorem in a Two-Dimensional Ising Model with Dipolar Interactions. https://doi.org/10.1103/physrevb.60.3013

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