Optical spectroscopy of ScNiSb and YNiSb intermetallic compounds

Experimental studies of the optical and dielectric properties of intermetallic half-Heusler compounds ScNiSb and YNiSb have been performed. The frequency dependences of optical constants – refractive indices and absorption coefficients, were measured using an ellipsometric method in the energy range of 0.08 – 5.64 eV. Using these parameters, the spectra of the real and imaginary parts of the complex permittivity, optical conductivity, reflectivity, and the function of characteristic electron energy losses are calculated. Based on a comparative analysis of experimental and theoretical optical conductivity spectra, the nature of interband light absorption in both materials is discussed. The semi-metallic properties of the compounds are manifested in the anomalous behavior of spectral characteristics in the infrared region of the spectrum.