The nonequilibrium critical dynamics of the two-dimensional XY model is investigated numerically through Monte Carlo simulations and analytically in the spin-wave approximation. We focus in particular on the behaviour of the two-time response and correlation functions and show that the ageing dynamics depends on the initial conditions. The presence of critical fluctuations leads to nontrivial violations of the fluctuation-dissipation theorem apparently reminiscent of the three-dimensional Edwards-Anderson spin glass model. We compute for this reason the finite-size overlap probability distribution function and find that it is related to the finite-time fluctuation-dissipation ratio obtained in the out-of-equilibrium dynamics, provided that the temperature is not very low.

Nonequilibrium critical dynamics of the two-dimensional XY model

SELLITTO, Mauro
2001

Abstract

The nonequilibrium critical dynamics of the two-dimensional XY model is investigated numerically through Monte Carlo simulations and analytically in the spin-wave approximation. We focus in particular on the behaviour of the two-time response and correlation functions and show that the ageing dynamics depends on the initial conditions. The presence of critical fluctuations leads to nontrivial violations of the fluctuation-dissipation theorem apparently reminiscent of the three-dimensional Edwards-Anderson spin glass model. We compute for this reason the finite-size overlap probability distribution function and find that it is related to the finite-time fluctuation-dissipation ratio obtained in the out-of-equilibrium dynamics, provided that the temperature is not very low.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11591/188733
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