Giant magnetisation step in Fe2: Molecular nanomagnets in the weak exchange limit F. El Hallak, P. Rosa, P. Vidal, I. Sheikin, M. Dressel and J. van Slageren EPL, 95 5 (2011) 57002 Published online: 10 August 2011 DOI: 10.1209/0295-5075/95/57002