[1] Alexandru Ioan Cuza Univ, Dept Solid State & Theoret Phys, Iasi 700506, Romania
[2] Univ Bordeaux 1, Inst Chim Mat Condensee Bordeaux, Grp Sci Mol, CNRS,UPR 9048, F-33608 Pessac, France
[3] Univ Versailles, Lab Magnetisme & Opt, CNRS, UMR 8634, F-78035 Versailles, France