Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.27: Poster

Thursday, February 28, 2008, 14:00–18:00, Poster B

Structural and magnetic properties of a betaine-bridged trimer Cu²⁺ spin system — •K. Remović-Langer¹, B. Wolf¹, L. Wiehl², E. Haussühl², B. Winkler², N. Hasselmann³, F. Sauli³, P. Kopietz³, and M. Lang¹ — ¹Physikalisches Institut, J.W. Goethe-Universität, Max-von-Laue-Str. 1, SFB/TR 49, D-60438 Frankfurt(M). — ²Institut für Mineralogie/Kristallographie, J.W. Goethe-Universität, Altenhöferallee 1, D-60438 Frankfurt(M). — ³Institut für Theoretische Physik, J.W. Goethe-Universität, Max-von-Laue-Str. 1, SFB/TR 49, D-60438 Frankfurt(M).

A new betaine complex of Cu(II) (S = 1/2), with the general formula 2b*3CuCl₂*2H₂O with b = betaine (C₅H₁₁NO₂), has been synthesized and characterized magnetically. The structure of this metal-organic compound consists of centrosymmetric trimer units in which the neighboring Cu(II) atoms are bridged by the carboxylate groups of two betaine molecules. All Cu(II) ions show a nearly planar quadratic environment. In the ab-plane, a two-dimensional network of hydrogen bonds connects each trimer with four other trimers in a nearly quadratic arrangement. The obtained magnetic properties of Cu-betaine complex can be satisfactorily explained by using a magnetic model of coupled spin S = 1/2 trimers sitting on a quadratic lattice with an intra-trimer antiferromagnetic (AF) Cu-Cu coupling of J/k_B = 14 K and weak inter-trimer AF interaction J′/k_B= 4 K.