1. Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften 8 Walther-Meissner-Strasse, Garching D-85748, Germany
2. Institute of Solid State Physics, Russian Academy of Sciences, 2 Academician Ossipyan Str., Chernogolovka 142432, Russia and Moscow Institute of Physics and Technology, 9 Institutskii per., Dolgoprudny 141700, Russia
3. Moscow Institute of Physics and Technology, 9 Institutskii per., Dolgoprudny 141700, Russia
4. Laboratoire National des Champs Magnétiques Intenses, CNRS, INSA, UJF, UPS, 9 Grenoble Cedex F-38042, France
5. Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1 ave. Academician Semenov, Chernogolovka 142432, Russia