ON THE RATIO BETWEEN THE MAXIMUM ABSORPTION FREQUENCY AND THE RESONANCE FREQUENCY OF COMPOSITE MAGNETIC FLUIDS
Pages 157-162
I.Malaescu, P. C. Fannin, C. N. Marin
Abstract
The magnetic fluid samples investigated in this study were three kerosene-based magnetic fluids, stabilised with oleic acid, denoted as F1, F2 and F3. Sample F1 was a magnetic fluid with Mn0.6Fe0.4Fe2O4 particles, sample F2 was a magnetic fluid with Ni0.4Zn0.6Fe2O4 particles and sample F3 was a composite magnetic fluid obtained by mixing a part of sample F1 with a part of sample F2, in proportion of 1:1. Starting from the Landau-Lifshitz equation, it is demonstrated that in the case of a magnetic fluid, the measured resonance frequency, ƒres is always different the corresponding maximum absorption frequency, ƒmax and the ratio,ƒmax/ƒres, increases approaching unity with increase of polarizing field, Hpol . Measurements of the frequency dependent, complex magnetic susceptibility, χ(ω)=χ'(ω)−iχ"(ω), in the GHz range, are used to investigate the effect which the mixing of two different magnetic fluids has on the dependence of the ratio ƒmax/ƒres on an external strong polarizing magnetic field.