Superconducting Gap and Pseudogap in Sm(O$_{1-x}$F$_x$)FeAs Layered   Superconductor from Photoemission Spectroscopy
  High resolution photoemission measurements have been carried out on non-superconducting SmOFeAs parent compound and superconducting Sm(O$_{1-x}$F$_x$)FeAs (x=0.12, and 0.15) compounds. The momentum-integrated spectra exhibit a clear Fermi cutoff that shows little leading-edge shift in the superconducting state which suggests the Fermi surface sheet(s) around the $\Gamma$ point may not be gapped in this multiband superconductors. A robust feature at 13 meV is identified in all these samples. Spectral weight suppression near E$_F$ with decreasing temperature is observed in both undoped and doped samples that points to a possible existence of a pseudogap in these Fe-based compounds. 
Haiyun Liu, Xiaowen Jia, Wentao Zhang, Lin Zhao, Jianqiao Meng,   Guodong Liu, Xiaoli Dong, G. Wu, R. H. Liu, X. H. Chen, Z....