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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Low-dimensional Systems - Materials 2
TT 28.5: Talk
Wednesday, March 28, 2012, 16:00–16:15, H 0104
Thermodynamic properties of the 1-dimensional Spin-1/2 compound Cs2CoCl4 in transverse magnetic fields — •Oliver Breunig1, Eran Sela2, Benjamin Buldmann2, Markus Garst2, Petra Becker3, Ladislav Bohatý3, Christian Dax1, Ralf Müller1, and Thomas Lorenz1 — 1II. Physikalisches Institut, Universität zu Köln — 2Institut für Theoretische Physik, Universität zu Köln — 3Institut für Kristallographie, Universität zu Köln
Cs2CoCl4 is known as a an example of a spin-1/2 XXZ model crystal. It contains CoCl4 tetrahedra, which form one-dimensional chains along the crystallographic b axis. The orbital groundstate of Co2+ is split by the crystal field into doublets and an easy-plane anisotropy of the magnetization is established. The ground-state doublet is separated from the first excited doublet state by approximately 15 K, in a way that at low-enough temperatures the system can be described by the one-dimensional spin-1/2 XXZ model. In literature, this model is typically studied for magnetic fields perpendicular to the easy-plane. For structural reasons, however, in Cs2CoCl4 the only principal magnetic field direction which is experimentally accessible lies within the easy-plane. Only few studies of the corresponding transverse field case are available so far. We compare experimental data of specific heat and thermal expansion in a temperature range from about 50 mK to 20 K to numerical calculations.
This work was supported by the DFG through SFB 608.