title: Influence of dipolar interaction on magnetic properties of ultrafine ferromagnetic particles
abstract: We use Monte Carlo simulations to study the influence of dipolar interaction and polydispersity on the magnetic properties of single-domain ultrafine ferromagnetic particles. From the zero field cooling (ZFC)/field cooling (FC) simulations we observe that the blocking temperature T(B) clearly increases with increasing strength of interaction, but it is almost not effected by a broadening of the distribution of particle sizes. While the dependence of the ZFC/FC curves on interaction and cooling rate are reminiscent of a spin glass transition at T(B), the relaxational behavior of the magnetic moments below T(B) is not in accordance with the picture of cooperative freezing.
authors.affiliation: Departamento de Fisica Aplicada, Universidade de Santiago de Compostela, Campus Universitario, 15706 Santiago de Compostela, Spain.
authors.initials: J
authors.lastname: Garcia-Otero
authors.initials: M
authors.lastname: Porto
authors.initials: J
authors.lastname: Rivas
authors.initials: A
authors.lastname: Bunde