Dipolar interactions induced order in assemblies of magnetic particles

We discuss the appareance of ordered structures in assemblies of magnetic particles. The phenomenon occurs when dipolar interactions and the thermal motion of the particles compete, and is mediated by screening and excluded volume effects. It is observed irrespective of the dimensionality of the system and the resulting structures, which may be regular or fractal, indicate that new ordered phases may emerge in these system when dipolar interactions play a significant role.