Dresden 2011 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 44: Poster Session Correlated Electrons
TT 44.50: Poster
Thursday, March 17, 2011, 10:00–13:00, P1
Thermodynamic properties of the XY-spin-1/2 chain system Cs2CoCl4 — •Oliver Breunig, Daniel Löwen, Ralf Müller, Oliver Heyer, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
Cs2CoCl4 contains CoCl4 tetrahedrons, which form one-dimensional chains along the crystallographic b axis. The orbital groundstate of Co2+ is split up by the crystal field into doublets and an easy-plane anisotropy of the magnetization is established. The lowest doublet is separated from the second by approximately 14 K, such that at low enough temperatures the system can be described by the one-dimensional spin-1/2 XY model. The intra-chain exchange constant being much stronger than the coupling between the chains suppresses the antiferromagnetic order to TN≃ 220 mK. Here, we present measurements of specific heat and magnetization in a temperature range from about 0.3 to 20 K. The one-dimensional magnetism is reflected by a pronounced maximum in cp around 1 K. The zero-field data are well described by numerical calculations yielding an intra-chain exchange constant J/kB≃ 2.5 K. In magnetic fields the specific heat changes drastically, as the system undergoes a quantum phase transition to a fully polarized state at fields of about 2 T. We compare our experimental data for different field directions to numerical calculations.
This work was supported by the DFG through SFB 608.