Observation of Multiple Superconducting Gaps in the Infrared   Reflectivity Spectra of Ba(Fe0.9Co0.1)2As2
  The results of infrared reflectivity measurements for the iron-based high-temperature superconductor Ba(Fe0.9Co0.1)2As2 are reported. The reflectivity is found to be close to unity at frequencies w lower than 2Delta/h (2Delta is the superconducting gap and h is Planck's constant). This is evidence for the s+/- or s+/+ symmetry of the superconducting order parameter in the studied compound. The infrared reflectivity spectra of Ba(Fe0.9Co0.1)2As2 manifest opening of several superconducting gaps at temperatures lower than critical Tc. 
Yu. A. Aleshchenko, A. V. Muratov, V. M. Pudalov, E. S. Zhukova, B. P.   Gorshunov, F. Kurth, K. lida
cond-mat.supr-con