Model of Electronic Structure and Superconductivity in Orbitally Ordered FeSe.

ABSTRACT

We provide a band structure with low-energy properties consistent with recent photoemission and quantum oscillation measurements on FeSe, assuming mean-field-like site- and/or bond-centered ferro-orbital ordering at the structural transition. We show how the resulting model provides a consistent explanation of the temperature dependence of the measured Knight shift and the spin-relaxation rate. Furthermore, the superconducting gap structure obtained from spin-fluctuation theory exhibits nodes on the electron pockets, consistent with the V-shaped density of states obtained by tunneling spectroscopy on this material, and the temperature dependence of the London penetration depth.