TEMPERATURE-DEPENDENCE ELECTRON-SPIN-RESONANCE SPECTRA OF A MAGNETIC FLUID

ESR spectra of a laboratory synthesized kerosene base magnetic fluid c ontaining ultrafine magnetic particles (average diameter of 100 A) of Zn0.1Fe0.9FeO4 are recorded at different temperatures. A narrow signal was observed above the melting point of the carrier liquid (200 K) wh ich can be attributed to a very small volume fraction of superparamagn etic particles in the system. The peak-to-peak line width for both low and high field cooled configurations show an increase with decreasing temperature. This observed behaviour has been explained by considerin g various energy terms which contribute to the line width.