Magnetoreflection and Magnetostriction in Ferrimagnetic Spinels CoFe2O4

It is shown that magnetoreflectance of natural light up to +4% exists in magnetostrictive ferrimagnetic spinel CoFe2O4 single crystal; this effect is associated with a change of the fundamental absorption edge, the impurity absorption band, and the phonon spectrum under the action of a magnetic field. The correlation between the field dependences of magnetoreflectance and magnetostriction has been established. The physical mechanisms responsible for the spectral and field peculiarities of magnetoreflection have been explained. It is shown that the magnetorefractive effect in CoFe2O4, which is associated with magnetoelastic properties of the spinel, amounts to +1.5 × 10–3 in magnetic fields exceeding the saturation field. Analysis of magnetooptical and magnetoelastic data has made it possible to estimate deformation potential as Ξu = 20 eV for the valence band of the spinel.