Fermi Surface Topology and Low-Lying Quasiparticle Dynamics of Parent Fe1+xTe/Se Superconductor

We report the first photoemission study of Fe1+xTe-the host compound of the newly discovered iron-chalcogenide superconductors (maximum T-c similar to 27 K). Our results reveal a pair of nearly electron-hole compensated Fermi pockets, strong Fermi velocity renormalization, and an absence of a spin-density-wave gap. A shadow hole pocket is observed at the X point of the Brillouin zone which is consistent with a long-range ordered magnetostructural ground state. No signature of Fermi surface nesting instability associated with Q=(pi/2,pi/2) is observed. Our results collectively reveal that the Fe1+xTe series is different from the undoped phases of the high T-c pnictides and likely harbor an unusual mechanism for superconductivity and magnetic order.