Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Low-Dimensional Systems: Poster Session
TT 72.13: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Thermal expansion and magnetostriction measurements of the mixed systems Cs2CuCl4−xBrx (0 ≤ x ≤ 4) — •Satya Krishna Thallapaka, Ulrich Tutsch, Lars Postulka, Bernd Wolf, Michael Lang, Natalia van Well, Franz Ritter, and Cornelius Krellner — Physics Institute, Goethe-University Frankfurt (M), SFB/TR 49, D-60438 Frankfurt (M), Germany
The mixed systems Cs2CuCl4−xBrx (0 ≤ x ≤ 4), including the two well-known end members Cs2CuCl4 and Cs2CuBr4, are classified as quasi-two-dimensional quantum antiferromagnets with different degrees of magnetic frustration. Due to a site-selective substitution of the halide atoms two distinct critical concentrations (x = 1 and x = 2) had been identified [1]. Especially the Cs2CuCl2Br2 compound exhibits the potential to be the system with the highest degree of frustration within this series. We present low-temperature thermal expansion measurements down to 40 mK and magnetostriction experiments up to 14 T on the Cs2CuCl2Br2 compound. While specific heat measurements reveal indications for magnetic order around 90 mK, no clear signatures were found in thermal expansion studies along the b axis. Here an in-T linear contribution was observed indicating a 1D character of the magnetic excitations. For fields above 5 T one finds a clear deviation from this linearity. These results are discussed with specific heat data and also compared with the thermodynamic properties of the pure Cs2CuCl4 compound.
[1] P. T. Cong et al., Phys. Rev. B 83, 064425 (2011)