[1] Russian Acad Sci, Ural Branch, MN Mikheev Inst Met Phys, 18 S Kovalevskaya St, Ekaterinburg 620108, Russia
[2] Iowa State Univ, Dept Phys & Astron, Ames Lab, Ames, IA 50011 USA
[3] Hokkaido Univ, Fac Sci, Dept Phys, Sapporo, Hokkaido 0600810, Japan
[4] Kurchatov Inst, Natl Res Ctr, Moscow 123182, Russia
[5] Natl Acad Sci Belarus, Inst Solid State Phys & Semicond, Minsk 220072, BELARUS