Terahertz-infrared electrodynamics of lead zirconate-titanate films on a platinum sublayer

The transmission-reflection spectra of a bilayer structure formed on a substrate of single-crystal silicon with transition layers (TiO$_2$–SiO$_2$), which consists of a PbZr$_{0.52}$Ti$_{0.48}$O$_3$ ferroelectric thin film and a polycrystalline platinum layer, have been measured in the frequency range of 10–6000 cm$^{-1}$. The frequency dependences of the real $\varepsilon'(\nu)$ and imaginary $\varepsilon''(\nu)$ parts of the permittivity have been simulated by the method of the dispersion analysis, and the parameters of lattice excitations in the lead zirconate-titanate film have been determined. It has been shown that the low-frequency terahertz dynamics exerts the decisive influence on the formation of the dielectric response over the entire studied frequency range.