Momentum dependence of the superconducting gap in Ba1-xKxFe2As2

D. V. Evtushinsky,1 D. S. Inosov,1,2 V. B. Zabolotnyy,1 A. Koitzsch,1 M. Knupfer,1 B. Buchner,1 M. S. Viazovska,3 G. L. Sun,2 V. Hinkov,2 A. V. Boris,2,4 C. T. Lin,2 B. Keimer,2 A. Varykhalov,5 A. A. Kordyuk,1,6 and S. V. Borisenko1 1Institute for Solid State Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany 2Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany 3Max-Planck-Institute for Mathematics, Vivatsgasse 7, 53111 Bonn, Germany 4Department of Physics, Loughborough University, Loughborough, LE11 3TU. United Kingdom 5BESSY GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany 6Institute of Metal Physics, National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine Received 24 September 2008; revised manuscript received 30 December 2008; published 17 February 2009