Aging in a two-dimensional Ising model with dipolar interactions

Abstract

Aging in a two-dimensional Ising spin model with both ferromagnetic exchange and antiferromagnetic dipolar interactions is established and investigated via Monte Carlo simulations. The behavior of the autocorrelation function ${C(t,t}_{w})$ is analyzed for different values of the temperature, the waiting time ${t}_{w}$ and the quotient $\ensuremath{\delta}{=J}_{0}{/J}_{d},$ ${J}_{0}$ and ${J}_{d}$ being the strength of exchange and dipolar interactions, respectively. Our results show that this nondisordered model presents a slow nonequilibrium dynamics which, depending on the values of \ensuremath{\delta}, is consistent either with a linear scaling ${t/t}_{w}$ of the correlation function or with a logaritmic scaling $\mathrm{ln}(t)/\mathrm{ln}{(t}_{w})$ which is usually associated with activated dynamics scenarios in disordered systems.