Remnant Fermi surface in a pseudogap regime of the two-dimensional Hubbard model at finite temperature |
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Authors: | T Saikawa A Ferraz |
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Institution: | (1) Laboratório de Supercondutividade, Centro Internacional de Fısica da Matéria Condensada, Universidade de Brasılia, CEP 70919-970 Brasılia-DF, Brazil, BR |
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Abstract: | A precursor effect on the Fermi surface in the two-dimensional Hubbard model at finite temperatures near the antiferromagnetic
instability is studied using three different itinerant approaches: the second order perturbation theory, the paramagnon theory
(PT), and the two-particle self-consistent (TPSC) approach. In general, at finite temperature, the Fermi surface of the interacting
electron systems is not sharply defined due to the broadening effects of the self-energy. In order to take account of those
effects we consider the single-particle spectral function A(, 0) at the Fermi level, to describe the counterpart of the Fermi surface at T = 0. We find that the Fermi surface is destroyed close to the pseudogap regime due to the spin-fluctuation effects in both
PT and TPSC approaches. Moreover, the top of the effective valence band is located around = (π/2,π/2) in agreement with earlier investigations on the single-hole motion in the antiferromagnetic background. A crossover
behavior from the Fermi-liquid regime to the pseudogap regime is observed in the electron concentration dependence of the
spectral function and the self-energy.
Received 8 September 2000 and Received in final form 20 December 2000 |
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Keywords: | PACS 71 27 +a Strongly correlated electron systems heavy fermions – 71 10 Fd Lattice fermion models (Hubbard model etc ) |
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