Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Molecular Magnetism
MA 40.8: Vortrag
Donnerstag, 14. März 2013, 17:00–17:15, H23
Quenching the quantum tunneling of magnetization in Mn6Cr single-molecule magnets — •Klaus Gieb1, Veronika Hoeke2, Wolfgang Kroener1, Thorsten Glaser2, and Paul Müller1 — 1Department für Physik, Universität Erlangen — 2Department Chemie und Pharmazie, Universität Bielefeld
We report on low-temperature magnetic measurements of Mn6Cr3+ single molecule magnets with different counter ions and crystal structures [1]. From SQUID susceptibility measurements it can be concluded that the ground state spin for these molecules is St = 21/2. Ac susceptibility measurements reveal a D parameter of around D = −0.23 K. By variation of the counter ions and solvent molecules, the molecular C3 symmetry can be slightly changed. This results in a tuning of the transversal anisotropy parameter that can be directly observed in low temperature single crystal Hall probe measurements: No tunneling steps were present in these measurements. Based on ac and dc relaxation measurements we show, that the transversal anisotropy is completely quenched in some cases. For the first time it is proved that a true C3 molecular symmetry can lead to a vanishing E term and therefore to stable magnetized state over month without an external field.
1. Hoeke, V., K. Gieb, P. Muller, L. Ungur, L.F. Chibotaru, M. Heidemeier, E. Krickemeyer, A. Stammler, H. Bogge, C. Schroder, J. Schnack, T. Glaser, Chemical Science, 3, 2868 (2012).