Plasmon-phonon contribution in the permittivity of ZnP2 single crystals in FIR at low temperatures

The permittivity model for ZnP2 crystals has been determined by reflectance measurements in the far infrared region. The dielectric permittivity is presented in the framework of the Drude-Lorentz model containing both plasmon and phonon contributions for two polarizations of incident light (E||c and E⊥c) at different temperatures. The temperature dependence of the oscillator parameters has been determined as well.