Magnetic structural characterization of Mg–Co–Cr ferrite by neutron diffraction

Abstract

Temperature-dependent neutron diffraction studies were done on the spinel oxide system Mg x Co 1− x Cr x Fe 2− x O 4 ( x=0.0, 0.25, 0.50, 0.75 and 1.0). Neutron diffraction data recorded in the temperature range 10–810 K were analyzed in the Rietveld method. Ordered sublattice magnetic moments of the five compositions of the spinel series at various temperatures were deduced from the analysis. A decreasing ordered moment with increasing substitution ( x) was found indicating a gradual weakening of ferrimagnetic order. Huge diffuse signals around the 1 1 1 Bragg diffraction peak were found in the neutron patterns of the composition x=1.0 below the Curie temperature manifesting a build-up of short-range magnetic spin clusters. The observed features suggest a canted ferrimagnetic structure in the composition range x⩽0.75 and a semi-spin glass-like transition at x=1.0.