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Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.77: Poster

Thursday, March 29, 2012, 15:00–19:00, Poster B

Spin diffusion in the Heisenberg Chain: a quantum Monte-Carlo study — •Yousef Rahnavard1,2, Björn Willenberg1,2, and Wolfram Brenig1,21Institute for Theoretical Physics, Technical University Braunschweig, D-38106 Braunschweig, Germany — 2Niedersächsische Technische Hochschule, NTH

We study the long-wavelength, finite frequency spectrum of the spin density response of the antiferromagnetic Heisenberg chain. Current proposals for this, based on results from bosonization, transfer-matrix renormalization group, and quantum Monte-Carlo (QMC), suggest a diffusive spectrum in the isotropic case with a diffusion kernel independent of frequency and momentum which is diverging in the low temperature limit. Here we extend on the previous QMC work, which has been restricted to a single system size only. Results will be presented for the low frequency current relaxation rate versus momentum and temperature, for various system sizes from N=64 to 256. Moreover signatures of anomalous diffusion will be checked for by considering potential power-law frequency dependence of the diffusion kernel.

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