A two-population analysis of the magnetic dipolar interaction in superparamagnetic systems: a Monte Carlo study

To understand the influence of the magnetic dipolar interaction on the blocking temperature (T(B)) of superparamagnetic systems, usual models treat the dipolar energy as an additional term to the single-particle anisotropy energy barrier. However, such approaches cannot describe non-monotonic T(B)(c) dependences as reported both experimental and theoretically. Therefore, alternative approaches should be explored. For such a purpose, in this work we investigate a simple approach based on splitting the total population of the system into two subgroups, depending on its relative orientation (parallel- or antiparallel-aligned) with respect to the applied magnetic field direction. The suitability of such approach was explored by means of a Monte Carlo technique that provided us with a good insight into the properties of the system. Our results indicate that this two-population analysis can be a promising way to understand the SPM behaviour of interacting nanomagnetic systems.