Dresden 2011 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 44: Poster Session Correlated Electrons
TT 44.48: Poster
Thursday, March 17, 2011, 10:00–13:00, P1
Thermal conductivity of BaCo2V2O8 — •Gerhard Kolland, Sandra Niesen, Martin Valldor, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Germany
BaCo2V2O8 is a quasi one-dimensional antiferromagnetic Ising-like spin-chain. The chain can be described by an effective S=1/2 1D XXZ model with coupling constant J≃65 K and anisotropy parameter є = 0.46. Parallel to the c axis the magnetization saturates at Hs || ≃ 23 T and perpendicular to the c axis at Hs ⊥ ≃ 41 T. At zero field, the system orders at TN = 5.4 K. The Néel order is suppressed by a magnet field with very different rates depending on the direction of the applied field. We measured the thermal conductivity parallel (κ||) and perpendicular (κ⊥) to the chains in the temperature range from room temperature down to 250 mK. For both directions, we observe a sharp anomaly at TN and two maxima, one in the ordered phase and one above. In the ordered phase, the thermal conductivity is isotropic (κ|| = κ⊥), while above TN, κ|| is significantly higher than κ⊥. As this may suggest an additional magnetic contribution to κ|| in the disordered phase, we compare our data to numerical calculations of the anisotropic κ using the 1D XXZ model Hamiltonian. Moreover, we analyze the field dependence of κ for different directions of the applied magnetic field.Supported by the DFG through SFB 608.