title: Multi-frequency EPR studies of a mononuclear holmium single-molecule magnet based on the polyoxometalate [Ho(III)(W5O18)2]9-.
abstract: 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 reveal a highly anisotropic eight line spectrum corresponding to transitions within the lowest m(J) = ±4 doublet, split by a strong hyperfine interaction with the I = 7/2 Ho nucleus (100% natural abundance). X-band EPR studies reveal the presence of an appreciable tunneling gap between the m(J) = ±4 doublet states having the same nuclear spin projection, leading to a highly non-linear field-dependence of the spectrum at low-frequencies.
authors.affiliation: Department of Physics, Florida State University, Tallahassee, FL 32306, USA.
authors.forename: Sanhita
authors.initials: S
authors.lastname: Ghosh
authors.forename: Saiti
authors.initials: S
authors.lastname: Datta
authors.forename: Lisa
authors.initials: L
authors.lastname: Friend
authors.forename: Salvador
authors.initials: S
authors.lastname: Cardona-Serra
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gaita-Ariño
authors.forename: Eugenio
authors.initials: E
authors.lastname: Coronado
authors.forename: Stephen
authors.initials: S
authors.lastname: Hill