Optical spectroscopy and electronic structure of the Er$_5$Ge$_3$ compound

The results of the study of the optical properties and electronic structure of the Er$_5$Ge$_3$ compound have been presented. In the wavelength range of 0.22–15 $\mu$m (0.083–5.64 eV), the optical constants have been measured, and the spectral and electronic characteristics have been determined. The spin-polarization calculations of the band spectrum have been performed in the local electron spin density approximation (LSDA) with a correction for strong correlations in the 4$f$ shell of the rare-earth atom (LSDA + U method). The main features of the experimental dispersion dependence of the optical conductivity in the region of quantum light absorption have been interpreted based on the results of calculations of the electron density of states.