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TT: Tiefe Temperaturen
TT 6: Postersitzung I: Josephsonkontakte und SQUIDs, Supraleitung: Theorie, Korrelierte Elektronen, Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt, Kohlenstoff-Nanoröhrchen, Quantenflüssigkeiten
TT 6.54: Poster
Monday, March 26, 2001, 14:30–17:00, Rang S\ 3
Heat transport in low-dimensional spin systems — •M. Hofmann1, T. Lorenz1, H. Kierspel1, O. Zabara1, A. Freimuth1, G. Uhrig2, H. Kageyama3, and A.A. Menovsky4 — 1II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany — 2Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Germany — 3Institut for Solid State Physics, University of Tokyo, Tokyo 106-8666, Japan — 4Van der Waals-Zeemann Laboratorium,, University of Amsterdam, 1018 XE Amsterdam, The Netherlands
During the last few years the thermal conductivity (k) of low-dimensional spin systems has attracted considerable interest. One of the reasons is that in these materials a large and unusual magnetic contribution to the heat current may be present. Another reason is that the phononic heat current probes the spectrum of magnetic excitations as well as the phonon-spin coupling. The latter is very important e.g. in the spin-Peierls compound CuGeO3. Both issues, the magnetic contribution to the heat current as well as the interaction of the phonons with magnetic excitations are to a large extend unexplored and not well understood. We present measurements of the thermal conductivity as a function of temperature and magnetic field up to 17T of the quasi- one-dimensional spin-Peierls system CuGeO3, of the two-dimensional dimer spin system SrCu2(BO3)2 and of Sr2CuO2Cl2, which is a model system for a 2D spin 1/2 Heisenberg antiferromagnet on a square lattice. The unusual thermal conductivity found in all cases is attributed to phononic and magnetic contributions to the heat current and/or strong scattering of phonons on magnetic excitations.