Temperature-dependent AC conductivities of BiCuOCh (Ch = Te, Se) in the terahertz range

We investigated the temperature-dependent optical conductivity of BiCuOCh (Ch = Te, Se) in the terahertz (THz) region. The optical conductivity of BiCuOSe increases with the temperature from 297 to 600 K, whereas that of BiCuOTe exhibits a different trend. In the THz frequency range of 0.4–1.6 THz, these materials show a conductivity increase as the frequency increases. The conductivity of BiCuOTe is greater than that of BiCuOSe. These results can be explained by a two-band structure model and the carrier-carrier scattering process. In addition, we fitted the experimental results to the Drude–Smith model to explain non-Drude like behavior. The dielectric constant of BiCuOTe depends on the frequency rather than on the temperature, whereas that of BiCuOSe depends on the temperature.