1. Department of Crystallography, St. Petersburg State University, University emb. 7/9, 199034 St. Petersburg, Russia
2. Kola Science Center, Russian Academy of Sciences, Apatity, Murmansk Region 184200, Russia
3. Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
4. Institute of Problems of Chemical Physics, Chernogolovka, Moscow Region 142432, Russia
5. Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, Adm. Makarova emb. 2, 199034 St. Petersburg, Russia