1. College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing 210037, P. R. China
2. Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, 620002 Ekaterinburg, Russia
3. Department of Physics, National Cheng Kung University, 1 Ta-Hsueh Road, 70101 Tainan, Taiwan
4. Consiglio Nazionale delle Ricerche (CNR)-Istituto Officina dei Materiali (IOM), Laboratorio TASC, Area Science Park S.S. 14 km 163.5, 34149 Trieste, Italy
5. Consiglio Nazionale delle Ricerche (CNR)-Istituto di Chimica dei Composti OrganoMetallici (ICCOM), Area della Ricerca di Firenze, via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
6. INSTM and Department of Physical and Chemical Sciences, University of L’Aquila, via Vetoio, 67100 L’Aquila, Abruzzo, Italy
7. Elettra-Sincrotrone S.C.p.A, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy
8. CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy