Field dependence of the dynamic properties of colloidal suspensions of Mn0.66Zn0.34Fe2O4 and Ni0.5An0.5Fe2O4 particles

Results of the magnetic field dependence of the complex susceptibility, of colloidal suspensions of Mn0.66Zn0.34Fe2O4 and Ni0.5Zn0.5Fe2O4 particles in a polarising magnetic field, H, covering the range 0-116 kA m(-1) are presented. Ferromagnetic resonance is observed for both samples and from plots of the dependence of the resonant frequency f(res),,, on polarising field, average values of anisotropy held, H-A,, and anisotropy constant, K, are determined. In the case of the Ni0.5Zn0.5Fe2O4 sample the variation in the ferromagnetic linewidth as a function of increasing polarising field shows a steady monotonic increase in contrast to that of the manganese zinc ferrite sample. This effect is attributed to the influence of the polarising field on the local canted structure. (C) 1999 Elsevier Science B.V. All rights reserved.