[1] CNRS, Inst Neel, F-38042 Grenoble, France
[2] Univ Grenoble 1, F-38042 Grenoble, France
[3] Ecole Normale Super, CNRS, UMR 8537, Lab Photon Quant & Mol, Cachan, France
[4] Univ Paris 06, CNRS, UMR 7618, Paris, France
[5] CNRS, UPR Condit Extremes & Mat Haute Temp & Irradiat 3, F-45071 Orleans, France