A ug 2 00 8 Formation of collective spins in frustrated clusters

J. Robert, V. Simonet, B. Canals, R. Ballou, E. Lhotel, C. Darie, P. Bordet, B. Ouladdiaf, M. Johnson, J. Ollivier, D. Braithwaite, H. Rakoto, and S. de Brion Institut NEEL, CNRS & Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France Institut Laue-Langevin, BP 154, F-38042 Grenoble Cedex, France. CEA-Grenoble, DRFMC/SPSMS/IMAPEC, 17 rue des Martyrs, F-38054 Grenoble cedex, France Laboratoire National des Champs Magnétiques Pulsés, 143 avenue de Rangueil, F-31400 Toulouse, France Grenoble High Magnetic Field Laboratory, CNRS, BP 166, F-38042 Grenoble, France (Dated: June 10, 2021)