Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.3: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Nonequilibrium steady-state density of states of the Falicov-Kimball model in the presence of a large electric field — •Alexander Joura1 and Jim Freericks2 — 1Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany — 2Georgetown University, Washington, DC 20057, U.S.A.
The electronic density of states (DOS) of the Falicov-Kimball model in a constant uniform electric field E is calculated using a Kadanoff-Baym-Keldysh nonequilibrium Green’s function technique and dynamical mean-field theory. When the electron-electron interaction U vanishes, the DOS is the Wannier-Stark ladder of delta functions spaced by the Bloch frequency. If U is increased, the delta function peaks initially broaden due to the scattering, but ultimately evolve into a continuous structure for large U’s. As E is increased from small values, where linear response theory can be used and we see broadened Wannier-Stark peaks, the DOS develops a shape with large peaks at miniband edges, separated in energy by U. We verify the accuracy of our calculations by checking the DOS against frequency-moment sum rules, and an independent transient-response calculation of the Green’s functions at long times. While our formalism has been applied to the Falicov-Kimball model, it can also be directly extended to other models like the Hubbard or periodic Anderson model, by using more complicated impurity problem solvers.