Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.41: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Pseudogap and magnetic incommensurability in the Hubbard model — •Michael Schreiber1 and Alexei Sherman2 — 1Institut für Physik, Technische Universität, Chemnitz, Germany — 2Institute of Physics, University of Tartu, Tartu, Estonia
The energy spectrum and the magnetic susceptibility of the two-dimensional repulsive Hubbard model are investigated with the use of a diagram technique for the case of strong correlations in which an expansion in powers of the hopping constant is used. For small lattices and high temperatures obtained results are in agreement with data of Monte Carlo simulations. It is shown that with departure from half-filling an additional narrow band arises near the Fermi level. By the dispersion, bandwidth and the variation with the electron concentration n this band is close to the spin-polaron band of the t-J model. For moderate doping a pseudogap appears near the Fermi level. The magnitude of the pseudogap and its change with n are similar to the pseudogap in hole-doped cuprate perovskites. With the departure from half-filling the low-frequency magnetic susceptibility becomes incommensurate and the incommensurability parameter grows with 1−n. The incommensurability, its dependence on the frequency and electron concentration resemble experimental results in lanthanum cuprates.