We report the full complex dielectric function of high-purity Ba0.68K0.32Fe2As2 single crystals with Tc=38.5K determined by wideband spectroscopic ellipsometry at temperatures 10≤T≤300K. We discuss the microscopic origin of superconductivity-induced infrared optical anomalies in the framework of a multiband Eliashberg theory with two distinct superconducting gap energies, 2ΔA≈6kBTc and 2ΔB≈2.2kBTc. The observed unusual suppression of the optical conductivity in the superconducting state at energies up to 14kBTc can be ascribed to spin-fluctuation–assisted processes in the clean limit of the strong-coupling regime.
|Number of pages||7|
|Journal||Physical review B: Condensed matter and materials physics|
|Publication status||Published - 2011|
Charnukha, A., Dolgov, O. V., Golubov, A. A., Matiks, Y., Sun, D. L., Lin, C. T., ... Boris, A. V. (2011). Eliashberg approach to infrared anomalies induced by the superconducting state of Ba(0.68)K(0.32)Fe(2)As(2) single crystals. Physical review B: Condensed matter and materials physics, 84(17), -. . https://doi.org/10.1103/PhysRevB.84.174511