https://doi.org/10.1140/epjb/e2003-00267-3
Charge instabilities in strongly correlated bilayer systems
Institut für Physik, BTU Cottbus, PBox 101344,
03013 Cottbus, Germany
Corresponding author: a goetz@physik.tu-cottbus.de
Received:
11
April
2003
Revised:
21
July
2003
Published online:
2
October
2003
We investigate the charge-instabilities of the
Hubbard-Holstein model with two coupled layers.
In this system the scattering processes naturally separate into
contributions which are either
symmetric or antisymmetric combinations with respect to exchange of the
layers. It turns out that the short-range strong correlations suppress
finite wave-vector nesting instabilities for both symmetries
but favor the occurrence of
phase separation in the symmetric channel.
Inclusion of a sizeable long-range Coulomb (LRC) interaction
frustrates the q=0
instabilities and supports the formation of incommensurate charge-density
waves (CDW). Upon reducing doping from half-filling and for small
electron-phonon coupling g
the CDW instability first occurs in the antisymmetric channel but
both instability lines merge with increasing g.
While LRC forces always suppress the phase separation instability in the
symmetric channel, the CDW period in the antisymmetric sector tends to
infinity (
) for sufficiently small Coulomb interaction.
This feature allows for the possibility of singular scattering
over the whole Fermi surface.
We discuss possible implications of our results
for the bilayer high-Tc cuprates.
PACS: 71.27.+a – Strongly correlated electron systems; heavy fermions / 74.72.-h – Cuprate superconductors (high-Tc and insulating parent compounds) / 74.25.Kc – Phonons
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003
