  We performed a Laser angle-resolved photoemission spectroscopy (ARPES) study
on a wide doping range of Ba1-xKxFe2As2 (BaK) and precisely determined the
doping evolution of the superconducting (SC) gaps in this compound. The gap
size of the outer hole Fermi surface (FS) sheet around the Brillioun zone (BZ)
center shows an abrupt drop with overdoping (for x > 0.6) while the inner and
middle FS gaps roughly scale with Tc. This is accompanied by the simultaneous
disappearance of the electron FS sheet with similar orbital character at the BZ
corner. These results browse the different contributions of X2-Y2 and XZ/YZ
orbitals to superconductivity in BaK and can be hardly completely reproduced by
the available theories on iron-based superconductors.
