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TT: Fachverband Tiefe Temperaturen

TT 47: Correlated Electrons: Spin Systems and Itinerant Magnets 2

TT 47.7: Vortrag

Freitag, 30. März 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.