A Simple Approach for the Magnetic Relaxation in Systems of Weakly-Interacting, Dispersive Nanoparticles in Applied Magnetic Field

Abstract

We investigated the magnetic relaxation of weakly interacting, dispersive, single domain Fe nanoparticles in Fe/Al2O3 composites prepared by sequential pulsed laser deposition on (100) Si substrates. The external magnetic field was oriented parallel to the substrate and applied in zero-field cooling conditions. It was found that the relax- ation of the irreversible magnetic moment mirr is similar to the well-known vortex-creep process in disordered super- conductors with poor supercurrent redistribution across the sample, leading to a power-law dependence of mirr(t), with a well-defined time t exponent.