1. SPSMS, UMR-E CEA/UJF-Grenoble 1, INAC, Grenoble, F-38054, France
2. Laboratoire National des Champs Magnétiques Intenses, UPR CNRS 3228, CNRS–UJF–UPS–INSA, 25 rue des Martyrs, B.P. 166, 38042 Grenoble cedex 9 France and 143 avenue de Rangueil, 31400 Toulouse, France
3. H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
4. IMR, Tohoku University, Oarai, Ibaraki 311-1313, Japan