Magneto-optical effects of aluminum and ferrous substituted cobalt ferrite

Abstract
The polar Kerr rotation of polycrystalline CoFe2−xAlxO4 (0≤x≤0.8) and CoxFe3−xO4 (0≤x≤1.0) was measured in the energy region 0.6 eV≤E≤5.5 eV. The Faraday rotation of thin polycrystalline films of CoFe2−xAlx O4 (x=0.1 and 0.6) was measured in the energy region of 0.6 eV≤E≤2.8 eV. The spectra in the energy region below 3 eV are discussed in terms of crystal field transitions of Co2+ (Td). Furthermore a new intense transition is observed around 2 eV. This transition is assigned to a charge transfer of Co2+ to Fe3+, both on the octahedral site.