A shadow gap in the over-doped (Ba1-xKx)Fe 2As2 compound

Abstract

The electron band around the M point in the compound, which is completely lifted up above the Fermi level for and hence its Fermi surface (FS) disappears, can still play the role of the main pairing resource by exchanging inter-band repulsive interaction with the main hole band (h1) around the point. This hidden electron band, which develops the superconducting order parameter (OP) but has no FS, displays a shadow gap feature which is easily detected by various experimental probes such as angle-resolved photoemission spectroscopy (ARPES) and tunneling measurements. We also show that the formation of the nodal gap with symmetry on another hole pocket (h2) around the point with a larger FS is stabilized due to the balance of the inter-band repulsive interactions from the main hole band (h1) with the OP , and the hidden electron band with the OP . © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.