Optical conductivity of intermetallic compounds YSn$_3$ and GdSn$_3$

The optical properties of binary cubic compounds YSn$_3$ and GdSn$_3$ were investigated by ellipsometric technique. The frequency dependences of the dielectric functions are determined in the energy range 0.083–5.64 eV. The features of the dispersion of optical conductivity in the intervals of intra- and interband light absorption are analyzed in detail. The nature of quantum light absorption in the studied materials is discussed on the basis of a comparative analysis of experimental and theoretical optical conductivity spectra. Plasma and relaxation frequencies of electrons are determined.