Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

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

TT 30.37: Poster

Donnerstag, 11. März 2004, 14:30–19:00, Poster A

Magnon heat transport of 2-leg spin ladders: Scattering on holes and static defects — •H. ElHaes¹, C. Hess², P. Ribeiro³, B. Büchner³, M. Hücker⁴, U. Ammerahl⁴, A. Revcolevschi⁴, F. Heidrich-Meisner⁵, and W. Brenig⁵ — ¹II. Physikalisches Institut, RWTH-Aachen, D-52056 Aachen, Germany — ²DPMC, University of Geneva, Switzerland — ³IFW-Dresden, D-01171 Dresden, Germany — ⁴Université Paris-Sud, France — ⁵Institut für Theoretische Physik, TU-Braunschweig D-38106 Braunschweig, Germany

We investigate scattering processes relevant for the magnon thermal conductivity κ_mag of the spin ladders in (Sr/Ca)₁₄Cu₂₄O₄₁. Based on a kinetic model we find that scattering is dominated by static defects and scattering on holes in the ladders. Our analysis reveals that the magnon mean free path l_mag can reach values up to 3000 Å. This value is confirmed by results obtained from Zn-doped materials where l_mag is approximately equal to the mean distance of Zn-ions in the ladders. The mean free path related to scattering on holes, l_h, is strongly doping and temperature dependent and is intimately related to the electrical resistivity. In particular, magnon-hole scattering becomes unimportant upon charge ordering in the ladders.