Institution: | a Department of Applied Physics, School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan b Division of Materials Physics, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan c Département de la Recherche Fondamentale sur la Matière Condenseé, SPSMS, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France |