Delocalized to Localized Transition in a Fe14 Molecular Nanomagnet

Molecular magnets are finite sized clusters of metal ions distributed within a crystalline host lattice such that their magnetic properties persist at the nano-scale. Delocalised electrons bound within a molecule presents a situation of interest for both technological applications and fundamental investigations. We have synthesised a mixed valence Fe14 molecule with a S=14 ground state. Our preliminary results indicate that the compound has a double potential well with a finite energy barrier to electron hopping between Fe sites. The electron hopping frequency is uniquely suited to the muon spectroscopic time scale. Our objective is to measure fluctuations in the local magnetic susceptibility to obtain direct experimental evidence of thermally activated valence delocalisation. This is the first time muons have been applied to investigate electron mobility within a molecular magnet.