Static magnetic properties of an ensemble of immobilized superparamagnetic particles with aligned easy magnetization axes

A. O. Ivanov^{1, 2} - E. A. Elfimova¹

¹ Ural Federal University, 51 Lenin Ave., Ekaterinburg, Russian Federation
² M.N. Mikheev Institute of Metal Physics UB RAS, 18 S. Kovalevskaya str., Ekaterinburg, Russian Federation

Abstract
Static magnetic properties of ensembles of immobilized superparamagnetic spherical particles are calculated theoretically for two types of texturing of easy magnetization axes when all easy axes are aligned (i) parallel and (ii) perpendicular to the direction of an external field. The interparticle dipole-dipole interaction is taken into account basing on the first order modified mean-field model, in the framework of which the orientation of the magnetic moment of a randomly chosen particle is influenced by an external magnetic field and by a total dipolar field produced by all other magnetic moments. Magnetization laws and initial magnetic susceptibilities are calculated for both texturing types as functions of the height of the magnetic crystallographic anisotropy energy barrier for internal superparamagnetic rotation of magnetic moments inside the particles. Figs 3, Refs 10.