Optical study of charge dynamics in CaCo₂As₂

We present an infrared spectroscopy study of charge dynamics in CaCo₂As₂ single crystal. In this material, the optical conductivity can be described by two Drude components with different scattering rates (1/τ): a broad incoherent background and a narrow Drude component. By monitoring the temperature dependence, we find that only the narrow Drude component is temperature-dependent and determines the transport properties. Especially a Fermi liquid behavior of carriers is revealed by the T² behavior in the dc resistivity ρ_n and scattering rate 1/τ_n, indicating a coherent nature of quasiparticles in the narrow Drude subsystem.