Magneto-optical properties of substituted cobalt ferrites: CoFe2−xMexO4 (Me=Rh3+, Mn3+, Ti4++Co2+)

Abstract

The Faraday rotation has been calculated at 1.55‐eV photon energy (800 nm wavelength) for various substitutions in CoFe₂O₄ from the optical constants and the Kerr rotation and ellipticity spectra of polycrystalline bulk samples. The Faraday rotation consists of contributions both from the Co²⁺→Fe³⁺ charge transfer transition on octahedral sites as well as from the Co^{2+ 4}A₂→⁴T₁ (P) crystal‐field transition on tetrahedral sites, both centered around 2‐eV photon energy. For the various substitutions the contribution of the crystal field transition to the Faraday rotation at 1.55 eV is determined by the amount of Co²⁺ on tetrahedral sites as well as the shift in energy of this transition upon substitution. A significant contribution of the ⁴A₂→⁴T₁ (P) transition to the Faraday rotation at 1.55 eV is reached in Rh³⁺ substituted CoFe₂O₄.