Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 26: Korrelierte Elektronen: Theorie II
TT 26.12: Vortrag
Donnerstag, 11. März 2004, 12:30–12:45, H18
Anomalous self-energy and pseudogap formation in the 2D Hubbard model — •Andrey Katanin1,2,3 and Arno Kampf1 — 1Institut fuer Physik, Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg, Germany — 2Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — 3Institute of Metal Physics, 620219 Ekaterinburg, Russia
We calculate [1] the self-energy in the weak-coupling regime of the t-t′ Hubbard model using the functional RG approach. The flow of the vertices is truncated at one-loop order. At this order and at van Hove (vH) band fillings the quasiparticle concept is not valid at kF=(π,0) due to either thermal excitations of electrons at the vH singularities (vHs) or pseudogap formation. At low temperature the quasiparticle weight along the Fermi surface continuously vanishes from a finite value at the zone diagonal towards the (π ,0) point. Away from vH band fillings the quasiparticle peak is formed inside a pseudogap of size Δ , and within a finite frequency window |ω |≪ Δ around the Fermi energy the electronic self-energy has the conventional Fermi-liquid characteristics. With increasing separation between Fermi level and vHs the spectral anomalies gradually disappear.
[1] A. A. Katanin and A. P. Kampf, cond-mat/0310112.