Super spin dimensionality of a mono-dispersed and densely packed magnetic nanoparticle system

摘要

The dynamics of a dense near mono-dispersed assembly of maghemite nanoparticles is investigated by measurements of the temperature dependence of the isothermal remnant magnetization induced by temporal application of weak magnetic fields at constant temperature.The results suggest that the dimensionality of the super spins of the particles is of Heisenberg character at high temperatures but crossover to become Ising like at lower temperatures.