Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: FS: Time-Resolved Spectroscopy in Correlated Electron Systems:
Experiment and Theory

TT 28.5: Topical Talk

Donnerstag, 25. März 2010, 11:30–12:00, H18

Relaxation of strongly correlated electron systems: Insights from nonequilibrium dynamical mean-field theory — •Martin Eckstein — Theoretische Physik, ETH Zürich, 8093 Zürich, Schweiz

Pump-probe experiments with femtosecond time-resolution provide a unique way to observe the nonequilibrium dynamics of correlated electron systems after a strong laser excitation, before the electrons have equilibrated and the lattice dynamics becomes dominant. The bare timescales for the electronic relaxation are set by the Coulomb interaction and the hopping amplitude. However, the formation of photo-excited states and the electronic thermalization are not well understood, and neither are the timescales involved in those processes. Nonequilibrium dynamical mean-field theory (DMFT) allows to address those fundamental questions. We have combined DMFT with a recently developed real-time Quantum Monte Carlo impurity solver to investigate the thermalization of correlated electrons in the Hubbard model [1]. We find that the relaxation behavior undergoes a qualitative change at an intermediate value of U. This transition, which coincides with a pronounced minimum in the thermalization time, occurs for rather general initial states, although the location of the transition depends on the initial state. We also discuss the possibility to observe similar relaxation phenomena in pump-probe experiments.

[1] M. Eckstein, M. Kollar, and P. Werner, Phys. Rev. Lett. 103, 056403 (2009); arXiv:0910.5674.