Joris van Slageren, University of Stuttgart, Germany
During the last decade much synthetic effort has been spent on preparing novel mononuclear coordination compounds, especially based on lanthanide ions, that show slow relaxation of the magnetisation. Experimental investigations of the electronic structure and, hence, of the origin of the slow magnetisation dynamics has lagged far behind.
We have investigated the electronic structures of the archetypical single ion magnets (NBu4)+[Ln(Pc)2]– and substituted derivatives by means of a wide range of spectroscopic methods, including far-infrared spectroscopy, magnetic circular dichroism, high-frequency EPR and inelastic neutron scattering. We were able to characterize definitively the ground multiplet structure of these systems, which are not amenable to luminescence studies, for the first time. We show that the Orbach mechanism of spin relaxation plays a major role in the spin relaxation, something which had not been demonstrated previously. Finally in a different series of single-ion magnets we have found microsecond quantum coherence up to room temperature.