Upper limit on spontaneous supercurrents in Sr2RuO4

J. R. Kirtley,1,2,3 C. Kallin,4 C. W. Hicks,1 E.-A. Kim,5,6 Y. Liu,7 K. A. Moler,1,5 Y. Maeno,8 and K. D. Nelson7 1Department of Applied Physics, Stanford University, Palo Alto, California 94305, USA 2IBM Watson Research Center, Yorktown Heights, New York 10598, USA 3Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands 4Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1 5Department of Physics, Stanford University, Palo Alto, California 94305, USA 6Stanford Institute of Theoretical Physics, Stanford University, Palo Alto, California 94305, USA 7Department of Physics, Pennsylvania State University, University Park, Pennsylvania, 16802, USA 8Department of Physics, Kyoto University, Kyoto 606-8502, Japan Received 25 April 2007; published 26 July 2007