Determination of the blocking temperature of magnetic nanoparticles: The good, the bad, and the ugly

I.J. BRUVERA; P. MENDOZA ZÉLIS; M. PILAR CALATAYUD; G. F. GOYA; F. H. SÁNCHEZ

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2015 vol. 118

0021-8979

A numerically solved two-level Stoner-Wohlfarth model with thermal agitation is used to simulate Zero Field Cooling (ZFC)?Field Cooling (FC) curves of monosize and polysize samples and to determine the best method for obtaining a representative blocking temperature TB value of polysize samples. The results confirm a technique based on the T derivative of the difference between ZFC and FC curves proposed by Micha et al. (the good) and demonstrate its relation with two alternative methods: the ZFC maximum (the bad) and the inflection point (the ugly). The derivative method is then applied to experimental data, obtaining the TB distribution of a polysize Fe3O4nanoparticle sample suspended in hexane with an excellent agreement with TEM characterization.