An investigation of the microscopic and macroscopic properties of magnetic fluids (original) (raw)

Physica B: Condensed Matter, 2007

Abstract

ABSTRACT Measurements are presented of the frequency and field dependent complex magnetic susceptibility, of three different magnetic fluids, over the frequency and polarizing field (H) ranges of 100 MHz to 6 GHz and 0–122 kA/m, respectively. The investigated samples were Isopar M-based magnetic fluids, with magnetite particles (sample S1), Ni0.5Zn0.5Fe2O4 particles (sample S2) and Mn0.66Zn0.34Fe2O4 particles (sample S3). In the investigated frequency range ferromagnetic resonance occurs at a frequency, fres, and a corresponding maximum absorption occurs at a frequency fmax. From a plot of fres against H, average values of the anisotropy constant, , anisotropy field, , and gyromagnetic ratio, γ are determined. From a plot of fmax/fres against H the damping parameter, α, is obtained. Also, for each sample, an estimate is made of the particles magnetic viscosity, ηm, together with τ0, the pre-exponential factor of Brown's equation for the Néel relaxation time, τN, of the magnetic moment of superparamagnetic particles and τN itself.

Iosif Malaescu hasn't uploaded this paper.

Let Iosif know you want this paper to be uploaded.

Ask for this paper to be uploaded.