Evidence from infrared spectra for the magnetic moment directions of CR cations in the spinel ferrites

Abstract Infrared spectra of samples of the (A)[B] 2 O 4 spinel ferrites MFe 2 O 4 (M=Fe, Co, Ni, Cu, Cr) were investigated. It was found that the wave number ( ν 2 ) corresponding to B–O–B bond vibrations increases with decreasing magnetic moments ( μ m2 ) of the M 2+ cations, where the magnetic moment of Cr 2+ cation is assumed to be antiparallel to the other cations. This assumption is derived from a magnetic ordering model for spinel ferrites proposed recently by our group.