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Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.73: Poster

Wednesday, March 24, 2010, 14:00–18:00, Poster D1

Magnetic properties of the new low-dimensional spin magnet α-Cu2As2O7 — •Yulieth Arango1, Evgenia Vavilova2, Olga Volkova3, Mahmoud Abdel-Hafez1, Matthias Weil4, Alexander Vasiliev3, Vladislav Kataev1, Rüdiger Klingeler1, and Bernd Büchner11Leibniz-Institut für Festkörper und Werkstoffforschung IFW Dresden, Dresden, Germany — 2Zavoisky Physical-Technical Institute of RAS, Kazan, Russia — 3Physics Faculty, Moscow State University, Moscow, Russia — 4Institute for Chemical Technology and Analytics, Vienna University of Technology, Vienna, Austria

The crystal structure of α-Cu2As2O7 consists of two-dimensional infinite sheets (ab-plane) of [CuO5] polyhedra stacked along the c-axis. The Cu2+ (3d5, S=1/2) ions are connected via oxygen ligands in the Cu-O chains along the diagonal of the ab-plane. In this work we study the interplay between the crystal structure and magnetism of α-Cu2As2O7 single crystals by measuring magnetic susceptibility, specific heat, high field electron spin resonance (HF-ESR), and nuclear magnetic resonance (NMR). The data reveal that in the spin sector Cu-O chains represent a realization of a quasi-one dimensional (1D) spin-1/2 anisotropic Heisenberg antiferromagnet with the nearest neighbor exchange constant J ∼ 160 K. Due to residual 3D interactions α-Cu2As2O7 orders antiferromagnetically at TN ≃ 11 K. Below TN two phases are identified: a collinear phase and a field B induced spin-flop phase at B > BC ≃ 1.8 T.

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