Influence of Force Constant on Surface Phonon Polariton Properties of Cubic ZnSi_(1-x)Se_x Crystals

摘要

In this paper, our attention is focused on the influence of force constant on surface phonon polariton (SPhP) properties of cubic ZnS_(1-x)Se_x mixed crystals. Two different force constants were used, i.e., one considers only the first nearest neighbour interactions and another considers up to the second nearest neighbour interactions. For the theoretical modelling, modified random element iso-displacement (MREI) model was used. The results revealed that the second nearest neighbour interactions assumption gives significant impact on composition dependence of optical phonon spectra in which it can produce theoretical results closer to experimental data. Because of the dependence of SPhP on optical phonon modes, it is expected that the SPhP properties are also sensitive to the force constant. The SPhP dispersion curves are calculated for both of the end member binary crystals (x = 0 and 1) and mixed crystal with composition x = 0.3,0.5, and 0.8. Finally, implication of the theoretical results on relevant experiment is discussed.