Infrared signature of the superconducting gap symmetry in iron-arsenide superconductors

Y. M. Dai, 2 B. Xu, B. Shen, H. H. Wen, 3 X. G. Qiu, and R. P. S. M. Lobo ∗ Beijing National Laboratory for Condensed Matter Physics, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5, France National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China (Dated: June 23, 2011)