On the resonant frequency of ferrofluids subjected to a constant polarising field

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

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

Abstract
Broad band measurements of the complex susceptibility, c(w) = c¢(w) - ic¢¢(w), of a colloidal suspension of magnetite in isopar M reveals the presence of ferromagnetic resonance in the form of the c¢(w) component going negative in the GHz region. The magnetic field dependence of this resonant frequency for six values of polarising fields in the approximate range 0 to 70, 000 A/m is presented. The data are also fitted to theoretical profiles generated by the equations of Raikher and Shliomis suitably adapted to include a distribution of particle anisotropy constant, K. Table 1, Figs 6, Refs 15.