[1] CSIC, Inst Ciencia Mat Barcelona, Barcelona, Spain
[2] Univ Malaga, Dept Quim Inorgan Cristalog & Mineral, Malaga, Spain
[3] CNRS, Lab Louis Neel, Grenoble, France
[4] CSIC, Inst Ciencia Mat Madrid, Madrid, Spain
[5] Inst Laue Langevin, Grenoble, France