Optical properties and electronic structure of the CeFeSi-type GdTiGe and GdTiSi compounds

The optical properties of the CeFeSi-type GdTiGe and GdTiSi compounds have been investigated in the spectral range λ = 0.22–16μm. The optical constants and parameters of charge carriers (plasma and relaxation frequencies) were determined for both alloys. A self-consistent calculation of the electronic structure of these compounds was performed using the LDA + U method. Total and partial densities of states have been calculated. A strong hybridization between the d-states of Gd and Ti was found and a significant width of the f-band was observed in calculations. The calculations indicate also that significant polarization of the Ti 3d electrons was occurred which may be related to the indirect exchange interaction with magnetic moments of Gd atoms. These data were used to interpret the dispersion of the optical conductivity of the compounds. Essential agreement with experiment was observed, especially for GdTiSi.