Dresden 2003 – scientific programme
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MA: Magnetismus
MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)
MA 14.138: Poster
Tuesday, March 25, 2003, 15:15–19:15, Zelt
Na-NMR on the cyclic spincluster Na@Fe6(tea)6 — •Erik Herrling, Roland Leppin, and Bernd Pilawa — Physikalisches Institut, Universität Karlsruhe (TH), Karlsruhe, Germany
In the spincluster Na@Fe6(tea)6 six FeIII-ions (spin5/2) are antiferromagnetically coupled in a cyclic structure (J/kB=-23K) with a Na-atom in the center of the iron ring. The static magnetic susceptibility for temperatures above T≈20K is similar to that of a spin-chain. The similarity of the static properties leads to the question, in which way the dynamics of the finite spin system corresponds to the dynamics of a spin-chain. The electronic spindynamics can be observed via NMR measurements.
We compare Na-NMR measurements at ν=53MHz (B=4.7T) in the temperature range between 4 and 300K with proton-NMR measurements at ν=53MHz (B=1.25T). The position of the comparatively narrow NMR-signal of Na follows the temperature dependence of the static magnetic susceptibility for temperatures below the maximum of the magnetic susceptibility (Tmax≈110K). Above Tmax the resonance position deviates from the course of the magnetic susceptibility which indicates an oscillation of the Na-atom. In contrast to T1−1 of the protons, T1−1 of Na increases monotonically with temperature and shows no maximum at T≈30K like T1−1 of the protons.