[1] Charles Univ Prague, Inst Phys, CZ-12116 Prague 2, Czech Republic
[2] CNRS UJF UPS INSA, Lab Natl Champs Magnet Intenses, F-38042 Grenoble, France
[3] Univ Strathclyde, SUPA, Dept Phys, Glasgow G4 0NG, Lanark, Scotland
[4] Ural Fed Univ, Ekaterinburg 620002, Russia
[5] RAS, Inst Solid State Chem, Ekaterinburg 620002, Russia
[6] Univ Pardubice, Fac Chem Technol, Inst Appl Phys & Math, Pardubice 53210, Czech Republic
[7] Inst Elect Mat Technol, PL-01919 Warsaw, Poland