Normal state charge dynamics of novel iron-based superconductor FeTe$_{0.87}$S$_{0.13}$ probed with infrared spectroscopy

We will present the results of our spectroscopic studies of novel iron-based superconductor FeTe$_{0.87}$S$_{0.13}$ with T$_c$ = 8 K. Infrared and optical measurements have been performed over a broad range of frequencies (50 - 50,000 cm$^{-1}$ and temperatures (10 - 300 K). Our results reveal unusual normal state: incoherent charge dynamics and absence of well defined quasiparticles. Unlike other iron-based superconductors, the structural and magnetic phase transitions at T$\simeq$ 30~K do not seem to have significant effect on optical properties of FeTe$_{0.87}$S$_{0.13}$.