Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 3: Spin-Systeme und itinerante Magnete

TT 3.12: Vortrag

Montag, 8. März 2004, 12:15–12:30, H18

Heat Transport in Low Dimensional Spin Systems — •C. Hess¹, H. ElHaes², P. Ribeiro³, B. Büchner³, F. Heidrich-Meisner⁴, W. Brenig⁴, M. Hücker⁵, U. Ammerahl⁵, and A. Revcolevschi⁵ — ¹Department of Condensed Matter Physics, University of Geneva, Switzerland — ²II. Physikalisches Institut, RWTH Aachen, Germany — ³IFW Dresden, Germany — ⁴Institut für Theoretische Physik, TU-Braunschweig, Germany — ⁵Laboratoire de Physico-Chimie des Solides, Université Paris-Sud, France

We present experimental results for the magnon thermal conductivity κ_mag of several low dimensional spin systems, like antiferromagnetic planes, ladders and chains. We focus on the quasi two dimensional antiferromagnet La₂CuO₄ and the spin ladder system (Sr,Ca,La)₁₄Cu₂₄O₄₁, where scattering of the magnetic excitations on static defects, phonons, magnons and holes is analyzed on basis of a kinetic model. The analysis yields for example an intimate relation of magnetic and electronic transport channels in the spin ladders and in both systems a strict limitation of the magnon mean free path l_mag by artificially induced non magnetic defects, i.e., l_mag≈ d_Zn−Zn at low temperatures, where d_Zn−Zn is the mean distance of doped Zn-ions in the low dimensional structures. The latter result is in stark contrast to recent model calculations for the heat transport in the spin ladders.