Study of the magnetization curves of magnetic fluids of anisotropic nanoparticles

Author: Archil Ugulava
Co-authors: M.Verulashvili, G.Mchedlishvili, Z.Rostomashvili, S.Chkhaidze
Keywords: ferromagnetism, superparamagnetism, magnetic fluids.
Annotation:

In magnetic liquids anisotropy energy of nanoparticles may exceed the energy of thermal fluctuations at room temperature, which can largely affect the magnetization process. In case of strong uniaxial anisotropy, a system of magnetic nanoparticles can be formally represented as a set of two thermodynamic subsystems. One subsystem is composed of particles with magnetic moments directed mainly along and the other - opposite to the magnetic field. With the increasing role of anisotropy the shape of the magnetization curve is increasingly different from conventional Langevin form and approaching the Brillouin curve for quantum particles having half spins. The similarity of the considered system with Brillouin one is of purely formal nature and it is explained by the analogy of existing system consisting of two thermodynamic subsystems with quantum macrosystems of two-level particles