On the frequency dependence of the dynamic properties of colloidal suspensions of nanometre-sized particles

P. C. Fannin¹ - S. W. Charles² - T. Relihan¹

¹ Department of Electronics and Electrical Engineering, Trinity College, Dublin 2, Ireland
² Department of Chemistry, University College of Norh Wales, Bangor LL57 2UW, UK

Abstract
Measurement of the complex magnetic susceptibility, c(w) = c (w) - ic (w), and complex permitivity, e(w) = e (w) - ie (w), of three ferrofluid samples of cobalt in diester, manganese ferrite in isopar M and magnetite in a PFPE carrier, with average particle diameter of 7.8 nm, 10.5 nm and 11.9 nm and approximate magnetization of 0.04 T, 0.036 T and 0.03 T, respectively are presented. Ferromagnetic resonance, indicated by the transition of the c (w) components to a negative value, is observed for all three samples. This resonance effect is examined in the light of the work of Raikher and Shliomis. The effect which conducting particles, such as cobalt particles, have on the dielectric properties is highlighted. Figs. 2, refs. 9.