Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 18: Correlated Electrons: Low-dimensional Systems - Materials 2
TT 18.8: Vortrag
Dienstag, 26. Februar 2008, 17:15–17:30, H 2053
Thermal conductivity of TiOX (X=Br,Cl) — •Nikolai Hlubek1, Christian Hess1, Bernd Büchner1, Michael Sing2, Ralph Claessen2, Sander van Smaalen3, and Paul van Loosdrecht4 — 1IFW Dresden, Germany — 2Experimentelle Physik 4, Universität Würzburg, Germany — 3Laboratory of Crystallography, Universität Bayreuth, Germany — 4Zernike Institute for Advanced Materials, University of Groningen, Netherlands
We report experimental results on the thermal conductivity κ(T) of the compounds TiOBr and TiOCl. Below room temperature the compounds undergo two phase transitions Tc2 and Tc1. Above Tc2 the compounds should contain S=1/2 spin-chains with JCl=676K and JBr=375K respectively formed by direct orbital overlap of the Ti-atoms. Below Tc1 the chains dimerise to form a non-magnetic ground state. Our data exhibits pronounced anomalies at Tc2 and Tc1 confirming the transitions being of second and first order respectively. Surprisingly, κ(T) appears to be dominated by phonon heat conduction, since we don’t find indications of significant magnetic contributions. This is in contrast to the expectation of a spin chain system. In this context we discuss possible scenarios to understand the unusual behaviour of the thermal conductivity.