through a van Hove Singularity in Sr2 yLayRuO4 K. M. Shen,* N. Kikugawa, C. Bergemann, L. Balicas, F. Baumberger, W. Meevasana, N. J. C. Ingle, Y. Maeno, Z.-X. Shen, and A. P. Mackenzie Departments of Applied Physics, Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C., V6T 1Z4, Canada School of Physics & Astronomy and Scottish Universities Physics Alliance, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, United Kingdom Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 OHE, United Kingdom National High Magnetic Field Laboratory, Florida State University, Tallahassee Florida 32306, USA International Innovation Center, Kyoto University, Kyoto 606-8501, Japan Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan (Received 26 March 2007; published 29 October 2007)