A shadow gap in the over-doped (Ba1-XKX)Fe2As2 compound

作者：Bang Yunkyu^*

来源：New Journal of Physics, 2014, 16(2): 023029.

DOI：10.1088/1367-2630/16/2/023029

• Fermi surface instability
• iron-based superconductor
• pairing symmetry
• Fe2As2
• nodal gap

The electron band around the M point in the (Ba1-xKx) Fe2As2 compound, which is completely lifted up above the Fermi level for x > 0.7 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 Gamma point. This hidden electron band, which develops the superconducting order parameter (OP) Delta(e) but has no FS, displays a shadow gap feature which is easily detected by various experimental probes such as angle-resolved photo-emission spectroscopy (ARPES) and tunneling measurements. We also show that the formation of the nodal gap Delta(nodal) with A(1g) symmetry on another hole pocket (h2) around the Gamma 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 Delta(h1) = Delta(+), and the hidden electron band with the OP Delta(e) = Delta(-).

• 出版日期2014-2-21