Fermi surface topology and low-lying quasiparticle dynamics of parent Fe${}_{1+x}$Te/Se Superconductor by orbital-polarization resolved ARPES

Abstract

We report the first photoemission study of Fe${}_{1+x}$Te - the host compound of the newly discovered iron-chalcogenide superconductors (maximum T${}_c$ $\sim$ 27K). 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 magneto-structural groundstate. No signature of Fermi surface nesting instability associated with Q=($\ddot{I}€$/2, $\ddot{I}€$/2) is observed. Our results collectively reveal that the Fe${}_{1+x}$Te series is dramatically different from the high T${}_c$ pnictides and likely harbor unusual mechanism for superconductivity and magnetic order.

10 pages, 4 Figures, Accepted for publications in Physical Review Letters (2009)