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TT: Fachverband Tiefe Temperaturen

TT 55: Correlated Electrons: Low-Dimensional Systems -Materials 2

TT 55.5: Vortrag

Donnerstag, 14. März 2013, 10:30–10:45, H21

Novel frustrated quantum antiferromagnets in the solid-solution Cs₂CuCl_4−xBr_xthrough site-selective halide substitution — •Bernd Wolf, Pham Thanh Cong, Natalia van Well, Franz Ritter, Wolf Assmus, and Michael Lang — Physikalisches Institut, Goethe-Universität, SFB/TR 49, D-60438 Frankfurt

Depending on the growing conditions, an A-type orthorhombic or a B-type tetragonal structure can be found in the solid solution Cs₂CuCl_4−xBr_x (0 x 4). Here we present measurements of the temperature-dependent susceptibility and isothermal magnetization on the B-type compounds x = 1.6 and 2.0 and compare these results with the magnetic properties recently derived for the A-type variant by Cong et al., Phys. Rev. B 83, 064425 (2011). We find that due to their different Cu coordination, these two structural modifications exhibit quite dissimilar magnetic properties. The tetragonal compounds can be classified as quasi-2D ferromagnets characterized by ferromagnetic layers with a weak antiferromagnetic inter-layer coupling, whereas the orthorhombic materials, notably the border compounds x = 0 and 4, are model systems for frustrated 2D Heisenberg antiferromagnets.