Optical constants of gadolinium at various temperatures from polarimetric measurements. (Magnetic ordering effects)

Optical constants n( omega ) and k( omega ) were calculated for gadolinium metal in the spectral range 1.5-5 Ev from a polarimetric method. For various temperatures corresponding to the ferromagnetic and paramagnetic states, reflectance measurements were performed, at a pressure near 10-9 Torr, on very thick opaque films. Two essential structures were found in the optical conductivity near 1.5 eV and 2.5 eV. The influence of magnetic ordering was discussed in the energy range investigated. The abscissa of the peak located near 1.5 eV in the ferromagnetic state is displaced towards 1.85 eV in the paramagnetic state. In the range which was investigated, no additional feature occurs between these two states as it is the case for lowest energies. The absorption peaks near 1.5 eV and 2.5 eV were interpreted in terms of bandstructure calculations and attributed to maxima in the joint density of states.