Intrinsic Faraday spectra of ferromagnetic rutile Ti1−xCoxO2−δ

Abstract

We have investigated the Faraday spectra of ferromagnetic rutile Ti1−xCoxO2−δ films grown on Al2O3 (0001). The Faraday spectra strongly depended on the film thickness, revealing the significant effect of the multiple reflections of light. The intrinsic Faraday spectra of rutile Ti1−xCoxO2−δ were corrected for this multiple reflection effect on the basis of an optical model and compared with the absorption spectra in detail. The quantitatively good correspondence between intrinsic Faraday ellipticity and optical band edge strongly suggests that rutile Ti1−xCoxO2−δ is an intrinsic ferromagnetic semiconductor. The exchange parameters, N0α and N0β, were estimated as the order of ∼0.1eV.