MOSSBAUER AND MAGNETIZATION STUDY OF THE MIXED SPINEL COFE2-XCRXO4

Mossbauer and magnetization measurements are performed at 300 K on the mixed spinel CoFe2-xCrxO4 with a selective Fe-dilution of B-sublattice on increasing Cr concentration X from 0 to 1. Magnetization results for X = 0 to 1 exhibit a collinear ferrimagnetic structure, while Mossbauer results indicate that on increasing Fe-dilution of the B-sublattice, the collinear ferrimagnetic phase breaks down at X > 0.8 before reaching the ferrimagnetic percolation limit as a result of the presence of competing exchange interactions. These results are explained in terms of Villain's model.