A Magnetic Superatomic Dimer with an Intense Internal Electric Dipole Moment

The electronic and magnetic properties of the ligand-decorated Fe₆S₈ cluster and fused superatomic dimer are investigated using first-principles density functional theory. It is shown that the redox properties of the Fe₆S₈ cluster can be effectively controlled by altering the nature of the attached ligands. Donor ligands such as phosphines reduce the ionization energy of the Fe₆S₈ cluster, whereas the acceptor ligands such as CO increase the electron affinity. Such variation in the redox properties of the Fe₆S₈ cluster is the result of the ligand-induced shift in the cluster's electronic levels, so the occupation number remains mostly unaffected, leading to a marginal change in the spin magnetic moment of the cluster. A combination of two identical Fe₆S₈ clusters decorated by unbalanced ligands results in a superatomic dimer with a massive dipole moment and a large spin magnetic moment. Donor ligands on one side of the superatomic dimer with acceptor ligands on the other cause significant intercluster charge transfer. The resulting superatomic dimer offers an interesting motif for spintronics-related applications.