POLARIZED NEUTRON STUDY OF THE MAGNETIZATION DENSITY DISTRIBUTION WITHIN A COFE2O4 COLLOIDAL PARTICLE .2.

We analyzed X-ray and polarized neutron powder diffraction data of fin ely divided CoFe2O4 particles coated with oleic acid and uncoated. The particles are characterized by a lognormal size distribution. Using a model assuming magnetically noninteracting superparamagnetic particle s, X-ray derived particle size distributions, and the existence of a m agnetically disordered surface layer, we are able to predict the obser ved polarized neutron (4,0,0) powder diffraction profiles of the coate d particles. The best fit requires a magnetically anomalous shell appr oximately 12 Angstrom thick. The sample of uncoated particles is compl icated, showing signs of ferromagnetic behavior possibly resulting fro m sintering.