We performed a laser angle-resolved photoemission spectroscopy (ARPES) study on a wide doping range of Ba 1-xK xFe 2As 2 (BaK) and precisely determined the doping evolution of the superconducting gaps in this compound. The gap size of the outer hole Fermi-surface (FS) sheet around the Brillouin zone (BZ) center shows an abrupt drop with overdoping (for x 0.6) while the inner and middle FS gaps roughly scale with T c. This is accompanied by the simultaneous disappearance of the electron FS sheet with similar orbital character at the BZ corner. These results indicate the different contributions of X2-Y2 and XZ/YZ orbitals to superconductivity in BaK and can hardly be completely reproduced by the available theories on iron-based superconductors.
|Physical Review B - Condensed Matter and Materials Physics
|出版済み - 2012 10月 10