Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 11: Postersitzung II (Metall-Isolator-Überg
änge, Phasenüberg
änge in Quantensystemen, Theorie: Systeme korrelierter Elektronen)
TT 11.44: Poster
Dienstag, 25. März 2003, 14:30–19:00, P2c, P2d
Heat and spin transport in one-dimensional spin-1/2 systems — •Fabian Heidrich-Meisner1, Andreas Honecker1, Daniel C. Cabra2, and Wolfram Brenig1 — 1Institut für Theoretische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig — 2Laboratoire de Physique, ENS-Lyon, 69364 Lyon, France
Recent transport measurements on quasi low-dimensional transition-metal compounds have revealed unusually large thermal conductivities which have been attributed to magnetic excitations.
Motivated by this observation we study the zero-frequency transport properties of frustrated and dimerized spin-1/2 chains. Using exact diagonalization of the complete spectrum on finite systems of up to 18 sites we present a detailed analysis of the Drude weight for both the thermal and spin conductivity. In particular, we investigate the dependence on frustration, dimerization, and exchange anisotropy at arbitrary temperatures. In the integrable case of the anisotropic chain, a comparison with results from the Bethe ansatz is given in the high and low temperature regime. An additional focus is on the non-integrable case in which we find indications for a vanishing of both Drude weights in the thermodynamic limit.