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TT: Tiefe Temperaturen

TT 30: Postersitzung IV: Kritische Ph
änomene, Quantenstörstellen, niederdimensionale Systeme

TT 30.32: Poster

Thursday, March 11, 2004, 14:30–19:00, Poster A

Thermal transport of one-dimensional spin systems in the presence of a magnetic field — •Fabian Heidrich-Meisner, Andreas Honecker, and Wolfram Brenig — Technische Universität Braunschweig, Institut für Theoretische Physik, Mendelssohnstraße 3, 38106 Braunschweig

Transport properties of one-dimensional spin-1/2 systems have attracted strong theoretical interest during the last years. Many studies have focussed on the question of possible dissipationless transport in nonintegrable models and recent results indicate that the thermal conductivity is nondiverging in dimerized and frustrated systems. In the integrable XXZ model, the thermal conductivity is divergent, characterized by a finite thermal Drude weight, due to the relation of the thermal current operator to conserved quantities. In particular, the temperature dependence of the thermal Drude weight at zero magnetic field has been studied in great detail. It is the purpose of this work to extent these results in two directions. First, we consider the influence of a magnetic field on the thermal Drude weight of the XXZ model. Second, we analyze the frequency dependence of the thermal conductivity of spin ladders and frustrated chains both at zero and finite magnetic field. In addition, we discuss possible implications of our results for the mean lifetime of the thermal current in the case of nonintegrable models.