Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 45: Correlated Electrons: Poster Session
TT 45.77: Poster
Donnerstag, 29. März 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 Brenig1,2 — 1Institute 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.