[1] Univ Karlsruhe, Inst Theoret Festkorperphys, D-76128 Karlsruhe, Germany
[2] Tohoku Univ, Inst Mat Res, Sendai, Miyagi 9808577, Japan
[3] Polish Acad Sci, Inst Mol Phys, PL-60179 Poznan, Poland
[4] Tohoku Univ, Grad Sch Informat Sci, Sendai, Miyagi 9808579, Japan
[5] Max Planck Inst Mikrostrukturphys, D-06120 Halle Saale, Germany
[6] Adam Mickiewicz Univ Poznan, Inst Phys, PL-61614 Poznan, Poland