Unusual Electronic Structure and Observation of Dispersion Kink in CeFeAsO Parent Compound of FeAs-based Superconductors

Abstract

We report the first comprehensive high-resolution angle-resolved photoemission measurements on CeFeAsO, a parent compound of FeAs-based high temperature superconductors with a magnetic-structural transition at $\ensuremath{\sim}150\text{ }\text{ }\mathrm{K}$. In the magnetic-ordering state, four holelike Fermi surface sheets are observed near $\ensuremath{\Gamma}(0,0)$, and the Fermi surface near $M(\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi},\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi})$ shows a tiny electronlike pocket at $M$ surrounded by four strong spots. The unusual Fermi surface topology deviates strongly from the band structure calculations. The electronic signature of the magnetic-structural transition shows up in the dramatic change of the quasiparticle scattering rate. A dispersion kink at $\ensuremath{\sim}25\text{ }\text{ }\mathrm{meV}$ is observed for the first time in the parent compound of Fe-based superconductors.