Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster Session I

MM 20.5: Poster

Dienstag, 24. März 2009, 14:45–16:30, P4

Spin-phonon scattering and heat transport in spin ladders — •Christina Seidler and Wolfram Brenig — Institute for Theoretical Physics, Technical University Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany

We study the spin-phonon dynamics and the heat transport of two-leg spin-1/2 ladders in the presence of a magnetoelastic deformation-potential coupling. In the limit of weak inter-rung exchange we employ a mapping of the spin degrees of freedom to a gas of non-interacting bond-bosons to describe the magnetic excitations. The coupled spin-phonon excitations are derived perturbatively and their spectra will be discussed as a function of momentum, frequency, temperature, system parameters and external magnetic fields. Both optical and acoustical phonons will be considered.

The heat transport will be investigated in the linear-response regime by evaluating the corresponding Kubo integrals. Results for the temperature and the magnetic field dependence of both, the magnetic and phononic heat conductance, will be presented. In particular the effect of the field-induced triplet softening will be regarded.

Our results will be put into the context of the anomalous magnetic heat transport of the spin-ladder compound Sr₁₄Cu₂₄O₄₁.