Effects of Magnetic Order on Refractive Index and Photoconductivity of Europium Chalcogenides

Abstract

The refractive index of the europium chalcogenides has been measured as a function of wavelength, temperature, and magnetic field and compared with dispersion theory. Attributing different oscillator strengths to the various substances, classical dispersion theory can account for the observed changes in the refractive index. To get more information about the electronic transitions involved, the spectral photosensitivity of EuO and EuS has been measured as a function of temperature and magnetic field. The results show that in EuO and EuS, electrons are optically excited into a conduction band both above and below TC. Spin-disorder scattering leads to large new magnetophotoelectric effects near the Curie point.