Dresden 2006 – scientific programme
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MA: Magnetismus
MA 37: Molecular Magnetism
MA 37.7: Talk
Friday, March 31, 2006, 12:15–12:30, HSZ 403
AC-susceptibility measurements of spinclusters in high magnetic fields — •Roland Leppin and Bernd Pilawa — Physikalisches Institut, Universität Karlsruhe (TH)
The Fe2(hpdta)1, Fe4(hpdta)2 and Fe6(hpdta)3 clusters denote systems of antiferromagnetically coupled magnetic ions with s=5/2, which are surrounded by organic ligands. Of these spin systems the static magnetic susceptibility and exchange coupling constants are known, but no ESR signal can be detected to gain access to the electronic level structure. However, spin dynamics are still accessible via levelcrossing experiments with high field ac-susceptibility measurements.
Therefore an experimental setup has been developed to measure ac-susceptibility in a dc-magnetic field from 0 to 20T. Initial zero field measurements of a Mn7 cluster support the expected paramagnetic blocking temperature behaviour. For the (hpdta)-systems it is expected to measure a peak in the ac-susceptibility, when the dc-field passes an electronic levelcrossing between the lowest energy level and the next higher excited state, causing a step-like increase in magnetization.