Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Bio- Molecular Magnetism
MA 33.9: Vortrag
Donnerstag, 26. März 2009, 12:15–12:30, HSZ 103
Effects of the Ligand Shell on the Single-Molecule Magnet Behavior in Co5 Clusters — •J. Nehrkorn1, O. Waldmann1, F. Klöwer2, Y. H. Lan2, and A. K. Powell2 — 1Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany — 2Institut für Anorganische Chemie, Universität Karlsruhe, D-76128 Karlsruhe, Germany
Enhancing single-molecule magnet (SMM) behavior in molecular nanomagnets to higher temperatures is one of the great aims in this field. Incorporating CoII ions, because of their high magnetic anisotropy, has recently attracted much interest. In this work we study three Co5 clusters which exhibit similar cores, but differ in their coordination spheres due to the use of different ligands. Our dc and ac magnetic data revealed that one compound is clearly a SMM, one is a weak SMM, and the third one is no SMM. We interpret the data on the basis of an effective-spin Hamiltonian, which reproduces the magnetic data well and allows us to understand the trend of SMM behavior. A subtle effect of highly anisotropic systems was observed: anisotropic ferromagnetic couplings together with highly anisotropic g matrices can yield susceptibility curves with a temperature dependence usually associated to antiferromagnetic interactions.