Berlin 2012 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 47: Correlated Electrons: Spin Systems and Itinerant Magnets 2
TT 47.7: Talk
Friday, March 30, 2012, 11:00–11:15, H 0104
Spin transport in the XXZ chain at finite temperature and momentum — •Robin Steinigeweg1 and Wolfram Brenig2 — 1J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia — 2Institute for Theoretical Physics, Technical University Braunschweig, Mendelssohnstr. 3, D-38106 Braunschweig, Germany
We investigate the role of momentum for the transport of magnetization in the spin-1/2 Heisenberg chain above the isotropic point at finite temperature and momentum. Using numerical and analytical approaches, we analyze the autocorrelations of density and current and observe a finite region of the Brillouin zone with diffusive dynamics below a cut-off momentum, and a diffusion constant independent of momentum and time, which scales inversely with anisotropy. Lowering the temperature over a wide range, starting from infinity, the diffusion constant is found to increase strongly while the cut-off momentum for diffusion decreases. Above the cut-off momentum diffusion breaks down completely.