Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 14: Molekularer Magnetismus
MA 14.5: Vortrag
Samstag, 5. März 2005, 14:45–15:00, TU H1012
1H-NMR on Fe6(tea)6 single crystals — •Roland Leppin, Lars Schnelzer, and Bernd Pilawa — Physikalisches Institut, Universität Karlsruhe (TH)
The Fe6(tea)6 cluster consists of 6 FeIII ions, which are linked by the (tea)-ligand (tri ethanol aminato) to a ringlike structure. The symmetry axis of the molecule is parallel to the hexagonal axis c of the crystal structure so that the molecules can be easily oriented with respect to an external magnetic field. The temperature dependence of the proton T1 rate has been measured for various orientations of the magnetic field. These measurements reveal a strong dependence of the T1 rate on the direction of the magnetic field. The temperature dependence of the T1 rate for perpendicular orientation (B⊥ c) shows the characteristic variation known for powder samples i.e. an exponential increase of the T1 rate at low temperature, a maximum of the T1 rate at ∼ 40 K and a linear increase for T>120 K. In general, the T1 rate increases, when the field is turned towards the c direction and the T1 peak disappears for parallel field orientation. The origin of the T1 anisotropy will be discussed in this contribution.