Extraction of blocking temperature distribution from zero-field-cooled and field-cooled magnetization curves

Superparamagnetic fluctuation of magnetic nanoparticles is studied. We examine the validity of the simplified approach using the difference between zero-field-cooled magnetization and field-cooled one. The results show that it is valuable for estimating the blocking temperature distribution of polydispersive particles even in magnetic fields, if both surface effects and inter-particle interactions are negligible.