Unusual Pseudogap-like Features Observed in Iron Oxypnictide   Superconductors
  We have performed a temperature-dependent angle-integrated laser photoemission study of iron oxypnictide superconductors LaFeAsO:F and LaFePO:F exhibiting critical transition temperatures (Tc's) of 26 K and 5 K, respectively. We find that high-Tc LaFeAsO:F exhibits a temperature-dependent pseudogap-like feature extending over ~0.1 eV about the Fermi level at 250 K, whereas such a feature is absent in low-Tc LaFePO:F. We also find ~20-meV pseudogap-like features and signatures of superconducting gaps both in LaFeAsO:F and LaFePO:F. We discuss the possible origins of the unusual pseudogap-like features through comparison with the high-Tc cuprates. 
Y. Ishida, T. Shimojima, K. Ishizaka, T. Kiss, M. Okawa, T. Togashi,   S. Watanabe, X.-Y. Wang, C.-T. Chen, Y. Kamihara, M. ...