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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.147: Poster
Dienstag, 27. März 2007, 15:00–19:00, Poster A
Magnetic properties of homo- [Ni(II)4] and heterotetranuclear [Fe(III)2Cu(II)2] high-spin molecular complexes — •Christian Golze1, Rüdiger Klingeler1,2, Bernd Büchner1, Vladislav Kataev1, Michel Goiran2, Jean M. Broto2, Harison Rakoto2, Berthold Kersting3, and Phalguni Chaudhuri4 — 1IFW Dresden, Germany — 2LNCMP Toulouse, France — 3Institute for Anorganic Chemistry, University of Leipzig, Germany — 4MPI for Bioinorganic Chemistry Mülheim, Germany
HF ESR and magnetization data of new multicenter complexes are presented. In compound (1) two Ni ions are coupled to a dimer via a diaminthio-bridge, and a pair of dimers is coupled in a single molecule via a µ1,3 azide bridge. Thus a single molecule spin cluster of a quadrangular shape comprising four Ni(II) (each S = 1) is formed. The magnetically active fragments Fe2Cu2 of (2) form the so-called butterfly-motive. The intramolecular exchange paths between Fe(III) and Cu(II) are provided by OH-, ON-, and O-bridges and yield competing FM and AFM exchange interactions. Both complexes exhibit magnetic ground states which have been characterized by magnetization measurements in fields < 52 T. ESR has been measured on the polycrystalline samples of (1) and (2) to determine the zero field splittings of the spin-levels and the g-factors. While the crystallites of (1) could be oriented in high fields yielding the possibility to compare experimental quasi single-crystal and powder-averaged ESR data with the theoretical model, the appearence of the low temperature spectra of (2) is of unexpected symmetric step-like shape.