Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 33: Bio- Molecular Magnetism
MA 33.3: Vortrag
Donnerstag, 26. März 2009, 10:45–11:00, HSZ 103
magnetic excitations and spin correlations in the spherical keplerate molecular magnet {Mo72Fe30} — •ZhenDong Fu1, Paul Kögerler1,2, Ulrich Rücker1, and Thomas Brückel1 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany — 2Institut für Anorganische Chemie, RWTH Aachen, D-52074 Aachen, Germany
As one of the biggest molecular magnets that have been synthesized, the polyoxomolybdate {Mo72Fe30} allows us to investigate a highly symmetric and frustrated spin structure and provides us an ideal test-bed for the theory on frustrated quantum spin systems. In our work, the low-field magnetic susceptibility measurement yields a Curie temperature about -20 K, indicating weak antiferromagnetic exchange interactions between the nearest neighbors. The low lying magnetic excitations of {Mo72Fe30} are characterized in terms of field-dependent heat capacity and inelastic neutron scattering measurements. The energy gaps resolved from the experimental data are located at about 0.1 and 0.7 meV, consistent with the quantum rotational band model for {Mo72Fe30} system [1]. The diffuse neutron scattering study with polarization analysis on {Mo72Fe30} polycrystals reveals characteristic spin correlations close to a coplanar three-sublattice ground state. Our observations agree with the previous theoretical model for this system, but also suggest that refinements should be done to the existing theoretical models. [1] J. Schnack, M. Luban and R. Modler, Europhys. Lett., 56 (6), pp. 863*869 (2001)