Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 22: Postersitzung III: Syst. korr. Elektr.: Theorie II (1-15), Metall-Isol.- und Phasenüberg
änge (16-33), SL: Massivmat., Bandl., Pinning, Vortexdyn., Transport, Korngr. (34-43), Niedrigdim. Syst., Magnetotransport (44-63)

TT 22.54: Poster

Donnerstag, 14. März 2002, 14:00–17:30, A

Thermal Transport in Transition Metal Oxides with Low-Dimensional Structures of Charge and Spin — •C. Hess^1,2, U. Ammerahl^2,3, C. Baumann^1,2, D. Bruns^1,2, D. Cassel², L. Colonescu², O. Friedt², H. el Haes¹, M. Hücker^1,3, B. Büchner¹, M. Braden⁴, A. Revcolevschi³, S-W. Cheong⁵, F. Heidrich-Meisner⁶, and W. Brenig⁶ — ¹II. Physikalisches Institut, RWTH-Aachen, 52056 Aachen — ²II. Physikalisches Institut, Universität zu Köln, 50937 Köln — ³Université Paris-Sud — ⁴LLB, CE Saclay, F-91191 Gif-sur-Yvette, France — ⁵Rutgers University, Piscataway, New Jersey 08854 — ⁶Institut für Theoretische Physik, Technische Universität Braunschweig, 38106 Braunschweig

Stripe dynamics and commensurabilty strongly affect the thermal conductivity κ in stripe ordering nickelates and manganites, but are of minor significance for understanding the unusual κ of doped La₂CuO₄. Another interesting aspect concerning κ of this materials is the large magnon thermal conductivity κ_mag which we observe at higher temperatures. We analyze κ_mag applying a kinetic model and find that the magnon mean free path l_mag depends linearly on the mean defect distance. An even larger κ_mag is found in the spin ladder system (Sr,Ca,La)₁₄Cu₂₄O₄₁. On basis of a kinetic approach we find an l_mag reaching almost 1000 lattice spacings in some of these materials. The analysis of the temperature dependence of l_mag in Sr_14−xCa_xCu₂₄O₄₁ suggests a temperature-driven transfer of holes from the chains into the ladders.