Intrinsic and collective effects in assemblies of nanomagnets

In this paper we review some results of our works on the magnetization processes in: i) Isolated nanomagnets, both in the one-spin approximation and as many-spin systems. Here, we focus on the intrinsic properties, e.g., those induced by finite-size, boundary and surface effects. We also investigate the crossover between the two regimes. ii) Assemblies of nanomagnets, also in the two situations. We focus on their behavior mainly due to dipole-dipole interactions. Then, we will comment on the interplay between these intrinsic and collective effects.