Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.158: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Electronic and magnetic properties of multinuclear Ni(II) complexes — •C. Golze^2,1, C. Mennerich¹, M. Bröckelmann^1,2, V. Kataev², H.-H. Klauss¹, B. Büchner², A. Wolter¹, S. Süllow¹, J. Litterst¹, R. Klingeler², S. Demeshko³, G. Leibeling³, F. Meyer³, and D.-J. Price⁴ — ¹Institut für Metallphysik und Nukleare Festkörperphysik, TU Braunschweig — ²Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden — ³Institut für Anorganische Chemie, U Göttingen — ⁴Department of Chemistry, Univ. of Glasgow, United Kingdom

We present thermodynamic and high field ESR studies of the magnetic behaviour of two newly synthesized Ni(II) S=1 molecular magnets. In Na₂Ni₂(C₂O₄)₃(H₂O)₂ Ni dimers are weakly coupled along one direction forming a S=1 two-leg spin ladder. Magnetic susceptibility data and results of tunable ESR at frequencies up to 600 GHz in fields up to 15 T enable the accurate determination of the magnetic interactions J_rung and J_leg, the local anisotropy parameters D and E as well as the estimate of the relative energies of the Ni orbital states. The measurements prove that this system is close to the dimer limit. In the tetranuclear Ni(II) complexes [L₂Ni₄(N₃)_5−i(O₂CR)_i] (ClO₄), i=2,4, three symmetric magnetic interaction paths are realized by azide groups. The magnetic susceptibility of these systems indicates an S=0 ground state. This is confirmed by a numerical analysis using a three-J approach and a uniaxial anisotropy D which reveals a combination of antiferromagnetic and ferromagnetic interactions between the individual metal ions. First ESR results on this system will be discussed as well.