A Note on Why Low-Symmetry Lanthanide Clusters Can Be Good Single Molecule Magnets

Lanthanide complexes with a low-symmetry ligand environment are frequently observed to exhibit good single molecule magnet (SMM) behavior, which is seemingly at odds with the established understanding that strong Ising-type magnetic anisotropy is essential. This and other paradoxical features of such clusters are shown to follow naturally from a semiclassical treatment of the ligand field, which becomes valid in the limit of large total angular momentum <i>J</i>. Quantum corrections are discussed qualitatively. The resulting physical picture offers clear insight into a broad class of lanthanide-based SMMs.