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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 Fe^III 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.