Neutron powder diffraction in molecule-based magnetic materials: Long- and short-range magnetic order

Neutron scattering has long been the ultimate technique of choice for defining the structures and excitations in magnetically ordered solids. Hence, it is surprising that neutron diffraction has not played a larger part in the rapidly growing field of molecule-based magnets. There are several reasons for this: large-volume unit-cells, frequency of low symmetry, containing a relatively low concentration of magnetic centers meaning that the magnetic contribution is a small fraction of the total scattering while the need to deuterate the organic ligands limits the available molecules. Nevertheless, it is possible to get information about short- and long-range ordering and this brief review summarizes the recent work on contrasting molecular magnetic materials: the weakly ferromagnetic Mn(II) organo-phosphonates; the bimetallic oxalato- and dithio-oxalato-honeycomb layer ferro- and ferrimagnets and a prototype for π-d ferrimagnetism in ion-radical salts.