Electron spin resonance study of a temperature sensitive magnetic fluid

Electron spin resonance spectra of a temperature sensitive magnetic fluid involving polydispersed Mn0.5Zn0.5Fe2O4 ferrite particles are scanned from 200 to 400 K. For such a polydispersed system, the deconvolutions of the spectra suggest coexistence of two different resonance modes: (i) a broad line due to ferrimagnetic resonance and (ii) a sharp line at g=2 due to intrinsic superparamagnetic phase. From the intensity variation of the line at g=2, it is found that the contribution due to the superparamagnetic phase increases with temperature. A study of peak-to-peak linewidth variation with temperature indicates that the weakening of the magnetic moment is responsible for the observed reduction in the linewidth. (C) 2000 American Institute of Physics. [S0021-8979(00)02817-6].