Interplay between the magnetic field and the dipolar interaction on a magnetic nanoparticle system: A Monte Carlo study

Abstract

We have studied the influence of the applied magnetic field on the blocking temperature (TB) of a fine magnetic particle system. By means of a Monte Carlo technique we have simulated zero field cooling (ZFC) curves under different applied fields, obtaining the respective TB as a function of H. We have focused our study on the limit H → HK (where HK is the anisotropy field), since the results found in the literature usually lack a detailed study of this range. The simulations were done at different sample concentration of the nanoparticles, with the purpose of observing how the magnetic dipolar interaction affects the field dependence of TB. The classical expression predicts TB to disappear for H ⩾ HK, independently of the dipolar interaction strength. Our simulations show that at strong interacting conditions TB exists even for fields H > HK.