Electronic structure of superconducting FeSe studied by high-resolution photoemission spectroscopy

We have performed soft x-ray and ultrahigh-resolution laser-excited photoemission measurements on tetragonal FeSe, which was recently identified as a superconductor. Energy dependent study of valence band is compared to band structure calculations and yields a reasonable assignment of partial densities of states. However, the sharp peak near the Fermi level slightly deviates from the calculated energy position, giving rise to the necessity of self-energy correction. We have also performed ultrahighresolution laser photoemission experiment on FeSe and observed the suppression of intensity around the Fermi level upon cooling.