Evidence for excluding the possibility of d-wave superconducting-gap symmetry in Ba-doped KFe2As2

We have investigated the superconducting (SC)-gap anisotropy for several Ba-doped KFe2As2 samples using laser-based angle-resolved photoemission spectroscopy. We show that the SC-gap anisotropy and node positions drastically change with a small amount of Ba doping. Our results totally exclude a possibility of d-wave symmetry and strongly suggest that both spin and orbital fluctuations are important for the pairing interaction in the Ba-doped K122.