Multi-frequency EPR studies of a mononuclear holmium single-molecule magnet based on the polyoxometalate [Ho(III)(W5O18)2]9-.

Continuous-wave, multi-frequency electron paramagnetic resonance (EPR) studies are reported for a series of single-crystal and powder samples containing different dilutions of a recently discovered mononuclear Ho(III) (4f(10)) single-molecule magnet (SMM) encapsulated in a highly symmetric polyoxometalate (POM) cage. The encapsulation offers the potential for applications in molecular spintronics devices, as it preserves the intrinsic properties of the nanomagnet outside of the crystal. A significant magnetic anisotropy arises due to a splitting of the Hund's coupled total angular momentum (J = L + S = 8) ground state in the POM ligand field. Thus, high-frequency (50.4 GHz) EPR studies reve…