Competition between Dipolar and Exchange Coupling in Fe19 High Spin Molecular Magnets

In a previous study of the S=35/2 Fe19 single molecule magnet we used WISH to get the 1.2 K ordering mode and LET to get the local field order parameter and magnetic excitations. Combining this data with Monte Carlo analysis we could deduce that, despite the presence of significant dipolar interactions due to the large spin, weak intermolecular interactions acting over distances of order 1 nm were the main factor controlling the ordering. To fully test this hypothesis, we need to shift the balance between dipolar and exchange interactions. Therefore, we are carrying out measurements for a Fe19 molecule with larger etheidi ligands in order to quantify directly the effect of driving the system more strongly towards a dipolar-dominated limit. The end result will be valuable insight into the structural and spatial dependence of weak long-ranged intermolecular superexchange interactions.