Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.69: Poster
Mittwoch, 13. März 2013, 15:00–19:00, Poster D
The spin Drude weight in the spin-1/2 XXZ chain: a combined exact diagonalization and time-dependent DMRG study — •Johannes Hauschild1, Christoph Karrasch2, Stephan Langer1,3, and Fabian Heidrich-Meisner1,4 — 1LMU Munich — 2University of California, Berkley — 3University of Pittsburgh, USA — 4FAU Erlangen-Nuremberg
Various theoretical approaches predict a finite Drude weight D for spin transport in the gapless phase of the spin-1/2 XXZ chain, suggesting ballistic transport properties. Here we address two open questions: first, the temperature dependence of the Drude weight and second, the particular point of an SU(2) symmetric exchange, for which there is no agreement as to whether D is finite or not. We compute the Drude weight at finite temperatures with two approaches [1]: time-dependent density matrix renormalization group simulations using purification [2] and exact diagonalization. For the latter, we compare finite-size data obtained in either the grand-canonical or the canonical ensemble. We argue that the grand-canonical data, obtained from averaging over all subspaces with different magnetizations, have a more systematic finite-size dependence than the canonical one. The results for D(T) from exact diagonalization and tDMRG are in good quantitative agreement in the massless phase.
We acknowledge support from the DFG through FOR 912.
[1] C. Karrasch, J. Hauschild, S. Langer, F. Heidrich-Meisner, in preparation
C. Karrasch, J. H. Bardarson, and J. E. Moore, Phys. Rev. Lett. 108, 227206 (2012)