OPTICAL-PROPERTIES OF WSI2

The optical properties of WSi2 single crystal were investigated between 0.01 and 23 eV. The near-normal-polarized reflectivity was Kramers-Kronig analyzed to determine the dielectric functions over the whole spectral range. Some constraints were imposed in order that the resulting spectra fit those directly measured by ellipsometry in the energy range from 1.4 to 4.9 eV. The optical response of polycrystalline films of WSi2 was also analyzed. Some differences between the single crystal and the thin-film optical functions are underlined, particularly near 0.5 eV, where a low-absorption region exists. Moreover, the electronic states and the optical properties of WSi2 were calculated within the local-density approximation using the semirelativistic linear-muffin-tin-orbital method. The band structures, the l-projected densities of states, the complex dielectric function, the optical conductivity, the optical reflectivity, and the electron energy-loss spectrum were evaluated in the energy range from 0 to 10 eV. The agreement with the experimental data is good.