Angle-resolved photoemission observation of isotropic superconducting gaps in isovalent Ru-substituted

N. Xu,1 P. Richard,1,* X.-P. Wang,1 X. Shi,1 A. van Roekeghem,1,2 T. Qian,1 E. Ieki,3 K. Nakayama,3 T. Sato,3,4 E. Rienks,5 S. Thirupathaiah,6 J. Xing,7 H.-H. Wen,7 M. Shi,8 T. Takahashi,3,9 and H. Ding1,† 1Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 2Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France 3Department of Physics, Tohoku University, Sendai 980-8578, Japan 4TRiP, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan 5Helmholtz-Zentrum Berlin, BESSY, D-12489 Berlin, Germany 6Institute for Solid State Research, IFW Dresden, D-01171 Dresden, Germany 7Center for Superconducting Physics and Materials, National Laboratory for Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, China 8Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland 9WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan (Received 17 December 2012; revised manuscript received 3 March 2013; published 18 March 2013)