Nonmonotonic relaxation in systems with reentrant-type interaction

Recently, interesting nonmonotonic time evolution has been pointed out in the experiments by Jonsson et al. and Jonsson et al. and also in the numerical simulation by Takayama and Hukushima, where the magnetic susceptibility does not monotonically relax to the equilibrium value, but moves to the opposite side. We study the mechanism of this puzzling nonmonotonic dynamical property in a frustrated Ising model in which the equilibrium correlation exhibits nonmonotonic temperature dependence (reentrant type). We study the time evolution of the spin correlation function after a sudden change of temperature. We find that the value of the correlation function shows nonmonotonic relaxation, and we analyze the mechanisms of the nonmonotonicity. We also point out that competition between different configurations generally causes nonmonotonic relaxation.