Monte Carlo simulation of the equilibrium spinglass phase in disordered assemblies of magneticnanoparticles

摘要

This chapter is about the collective effects that are brought about by dipole-dipoleinteractions in disordered assemblies of magnetic nanoparticles (NP). We focus on NPs which havesingle magnetic domains and large uniaxial anisotropies. We first discuss time dependent propertiesof these systems, such as the zero field cooled (ZFC) and field cooled (FC) magnetic susceptibilityand aging, and report some results we obtain making use of the Metropolis Monte Carlo algorithm.For equilibrium behavior, we turn to the parallel tempered Monte Carlo method. A brief introductionto the method is followed by equilibrium results we have recently obtained, mainly, systems ofmagnetic dipoles with random anisotropy axes have, (a) below some non-zero temperature Tr, athermodynamic spin glass phase in three dimensions, but (b) in one layer assemblies, a spin glassphase only at or near zero temperature.