A microscopic approach to heating rate of ferrofluid droplets by a magnetic field

Agradecimentos: E.C.S. acknowledges support from the CNPq agency under Grant No. 307466/2016-7. P.A.O. acknowledges financial support from FONDECYT under Grant No. 1140571. F.F.F. and E.C.S. acknowledge CAPES agency financial support (No. CAPES PNPD 028/2010) Abstract: In this work, we study the heating process of colloidal ferrofluids by a magnetic field. The heating of the fluid occurs by the magnetic relaxation of the nanoparticles which provide thermal energy for the host liquid. In the limit of small volumes, the relaxation process occurs through the Neel mechanism since the magnetic nanoparticles present superparamagnetic behavior. Within this limit, we have used a microscopic model for the coupling to phonons and external magnetic field in order to model the relaxation mechanism and to obtain an expression for the heating rate of the fluid as a function of microscopic parameters. The analysis allows determining appropriate conditions for an optimal heating rate for ferrofluids based on superparamagnetic nanoparticles CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado