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MA: Fachverband Magnetismus
MA 4: Bio- und molekularer Magnetismus
MA 4.9: Talk
Monday, March 7, 2016, 11:45–12:00, H33
Origin of the high blocking temperature in the Tb2N23− single molecule magnet — •Krunoslav Prsa1, J. Nehrkorn1, S. Nekuruh1, J. Corbey2, J.D. Rinehart3, T. Guidi4, J.R. Long3, W.J. Evans2, and Oliver Waldmann1 — 1Physikalisches Institut Universität Freiburg, Germany — 2Department of Chemistry, University of California, Irvine, USA — 3Department of Chemistry, University of California, Berkeley, USA — 4ISIS Facility, STFC Rutherford Appleton Laboratory, UK
The single molecule magnets containing magnetic rare-earth ions may lead to practical applications. The main challenge — weak interaction between the 4f–electrons — was recently overcome in an N23− radical–bridged dinuclear lanthanide molecular complex, resulting in a world record high blocking temperature of 14.3 K in Tb2N23−. We recorded the inelastic neutron scattering (INS) data on this molecule, its parent compound Tb2N22− and non-magnetic analogue Y2N23−. In addition to ligand field levels, we observed excitations due to the exchange coupling. We present our fits to the INS spectra and thermodynamical data. Compared to the parent compound, the N23− radical bridge brings two changes: (1) Its additional electronic charge influences the Tb3+ single ion ground state. (2) Its additional electron serves as an S=1/2 magnetic bridge between the terbium magnetic moments and hence enhances their effective magnetic interaction. Our simplified model compromises between a reduced number of parameters and the preservation of the structural information to carefully disentangle the two aforementioned effects.