MAGNETIC-PROPERTIES OF THE MINED SPINEL COFE2-XCRXO4

The crystal and magnetic properties of the Cr-substituted disordered s pinel system CoFe2-xCrxO4 (x = 0-1.6) are investigated by means of X-r ay, magnetization, Mossbauer effect and AC susceptibility measurements Variations of magnetic moment per formula unit measured at 80 K with Cr-content obtained from magnetization and Mossbauer data for x = 0-0. 6 display a discrepancy between them, thus exhibiting a significant ca nting on the B-site which is satisfactorily explained on the basis oi the non-collinear spin ordering model of random canting. Magnetization and Mossbauer results also show a sudden change near x > 0.6 indicati ng a change in magnetic structure from non-collinear to possibly colli near for x = 0.8-1.6. The AC susceptibility indicates a paramagnetic - -> unstable ferrimagnetic --> cluster spin glass-type transition as th e temperature is lowered for I = 0-1.2. The further increase in x from x > 1.2 increases frustration and disorder in the system supressing t he ferrimagnetic ordering and the system approaches a cluster spin gla ss-type ordering at x = 1.4-1.6 as reflected in AC susceptibility and Mossbauer spectra.