Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 4: Bio- und molekularer Magnetismus

MA 4.9: Vortrag

Montag, 7. März 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.