Superparamagnetic fluctuation in magnetic nanoparticles: an approach to extremely slow relaxation

A new approach to clarify, without a knowledge of the system´s initial and final states, the field-dependence of the extremely slow relaxation due to the superparamagnetic fluctuations is proposed. The procedure is subsequently applied to a typical magnetic nanoparticle assembly. This approach would prove to be helpful in studying current magnetic recording media approaching the thermal instability limit.