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TT: Fachverband Tiefe Temperaturen

TT 20: Correlated Electrons - Poster Session

TT 20.45: Poster

Mittwoch, 28. März 2007, 14:00–17:45, Poster A

Structural and magnetic dimers in the spin-gapped system CuTe₂O₅ — •Hans-Albrecht Krug von Nidda¹, Joachim Deisenhofer², Rushana Eremina^1,3, Tatiana Gavrilova³, Mike Whangbo⁴, and Alois Loidl¹ — ¹Experimental Physics V, Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany — ²Département de Physique de la Matière Condensée, Université de Genève, CH-1211 Genève 4, Switzerland — ³E. K. Zavoisky Physical-Technical Institute, 420029 Kazan, Russia — ⁴Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA

We investigate the magnetic properties of the system CuTe₂O₅ by susceptibility and electron spin resonance ESR measurements. The anisotropy of the effective g-factors and the ESR linewidth indicates that the anticipated structural dimer does not correspond to the singlet-forming magnetic dimer. Moreover, the spin susceptibility of CuTe₂O₅ can only be described by taking into account interdimer interactions of the same order of magnitude than the intradimer coupling. Analyzing the exchange couplings in the system we identify the strongest magnetic coupling between two Cu ions to be mediated by a super-superexchange interaction via a bridging Te ligand, while the superexchange coupling between the Cu ions of the structural dimer only results in the second strongest coupling.