https://doi.org/10.1007/PL00011093
Remnant Fermi surface in a pseudogap regime of the two-dimensional Hubbard model at finite temperature
Laboratório de Supercondutividade,
Centro Internacional de Física da Matéria Condensada,
Universidade de Brasília,
CEP 70919-970 Brasília-DF, Brazil
Corresponding author: a tsaikawa@alles.or.jp
Received:
8
September
2000
Revised:
20
December
2000
Published online: 15 March 2001
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 
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
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.
PACS: 71.27.+a – Strongly correlated electron systems; heavy fermions / 71.10.Fd – Lattice fermion models (Hubbard model, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001
