Magnetic relaxation of a one-dimensional model for small particle systems with dipolar interaction: Monte Carlo simulation

Abstract

Monte Carlo simulations have been performed to study the magnetic relaxation of a small particle system with dipolar interaction. The simulated system is a simplified version of the real situation in a small particle system with a random distribution of anisotropy axes and long range dipolar interaction among the particles. This model consists on a one-dimensional Ising model with dipolar interaction and a distribution of uniaxial anisotropy strengths. The anisotropy axes were considered perpendicular to the line connecting the spins. These choices allow us to focus on the influence of the demagnetizing part of the dipolar interaction on the magnetic relaxation by taking into account the main features of the system. The Tln(t/τ0) scaling variable is used to determine the effective distribution of energy barriers for the different interaction strengths showing an enhancement in the number of the lowest energy barriers as the interaction strength is increased. Moreover, the histograms of the energy barrier distribution as a function of the time are analyzed and this study leads to a deeper knowledge of the microscopic processes involved in the magnetic relaxation.