Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 27: Bio- and Molecular Magnetism
MA 27.8: Vortrag
Donnerstag, 28. Februar 2008, 16:15–16:30, EB 202
Spin-dynamics of ferric wheels in high magnetic fields — •Lars Schnelzer and Bernd Pilawa — Physikalisches Institut, Universität Karlsruhe (TH), D-76131 Karlsruhe
The dynamic properties of the antiferromagnetic cyclic hexanuclear iron(III) complexes 23Na/7Li@Fe6(tea)6 have been studied by means of nuclear magnetic resonance. We analyzed the longitudinal relaxation rate T1−1 of the central alkali ions 23Na and 7Li in the magnetic field range up to 20 T at a temperature of 2 K. The T1−1 measurements reveal the influence of the levelcrossing between the S=0 and S=1 states by an enhanced relaxation rate, as well as a strong decrease of the relaxation rate at characteristic fields between level crossings. In comparison with the calculated fluctuation spectrum of the electronic spins this suppression of the T1-rate indicates an extremely reduced line width of the electronic resonance around ω=0 (the so called ω0-resonance).