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MA: Fachverband Magnetismus

MA 33: Bio- Molecular Magnetism

MA 33.2: Talk

Thursday, March 26, 2009, 10:30–10:45, HSZ 103

Magnetic properties of planar TM-Ni binuclear single molecular magnets — •Ulf Wiedwald¹, Florian Mögele², Bernhard Rieger³, and Paul Ziemann¹ — ¹Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany — ²Institut für Materialien und Katalyse, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany — ³WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching bei München

Single molecular magnets are fascinating because of various possible coupling schemes between magnetic sites and resulting differences of the total magnetic moment, magnetic anisotropy and ordering temperature. Planar TM-Ni metallo-organic molecules (TM=V,Mn,Fe,Co,Ni,Cu) are synthesized each consisting of two magnetic sites and two identical alkyl chains forming a V-shape molecule. Dried powders are investigated by SQUID magnetometry. We find a resulting magnetization ranging from 0.2 µ_B/molecule for V-Ni molecules to 1.7 µ_B/molecule for Co-Ni molecules at B= 5.5T and T = 2K. Temperature-dependent susceptibility measurements suggest antiferromagnetic coupling of the two magnetic sites at T = 2K while at higher temperature a transition to ferromagnetic coupling is likely. The ordering temperatures are found between 9 and 34 K for Ni-Ni and Mn-Ni molecules, respectively.