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TT: Fachverband Tiefe Temperaturen

TT 28: Correlated Electrons: Low-dimensional Systems - Materials 2

TT 28.2: Talk

Wednesday, March 28, 2012, 15:15–15:30, H 0104

S=5/2 spin-chain Heisenberg systems SrMn₂V₂O₈ and BaMn₂V₂O₈ — •Sandra Niesen, Gerhard Kolland, Oliver Heyer, Martin Valldor, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln

Low-dimensional magnetic systems are commonly studied due to their interesting magnetic properties. For small spin values (S=1/2 or 1), the groundstate and the low-lying excitations are often dominated by strong quantum fluctuations, while a more classical behavior is expected for systems with larger spins. In this context, the series AM₂X₂O₈ (A = Ba, Sr, Pb; M = Cu, Co, Ni, Mn; X = V, As) are of particular interest. Depending on the transition metal, different spins are realized and the structure contains screw chains of octahedrally coordinated M²⁺ ions along the c axis of the tetragonal structure. These chains are spatially separated by a nonmagnetic matrix, resulting in a quasi-1D magnetic system. The Heisenberg S=5/2 system BaMn₂V₂O₈ shows low-dimensional behavior with a broad maximum of χ (T) around 170 K but finally orders antiferromagnetically at 37 K. Up to now only few studies of polycristalline BaMn₂V₂O₈ were available [1]. Large single crystals of BaMn₂V₂O₈ and of the new compound SrMn₂V₂O₈ were prepared. The crystal structure and the basic physical properties of this new compound will be presented [2].
This work is supported by the DFG through SFB 608.
[1] Z. He et al. Solid State Comm. 141 (2007) 22
[2] S.K. Niesen et al. J. Mag. Mag. Mat. 323 (2011) 2575