The in-plane complex optical properties of the iron-chalcogenide superconductor FeTe_o55Se_o45have beendetermined above and below the critical temperature T_c=14 K. At room temperature the conductivity isdescribed by a weakly interacting Fermi liquid; however, below 100 K the scattering rate develops a frequencydependence in the terahertz region, signaling the increasingly correlated nature of this material. We estimatethe dc conductivity crd_c(T≥ 7c)≈3500 ± 400Icm-Iand the superfluid density P,0≈9 1 X 106cm-2,which places this material close to the scaling line pc/8 ≈8.1deTc. for a BCS dirty-limit superconductor.Below T. the optical conductivity reveals two gap features at Δ1,2≈2.5 and 5.1 meV.
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