Charge instabilities in strongly correlated bilayer systems

Abstract

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 (q_c -> 0) 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.

14 pages, 8 figures, accepted for EPJ B

References in corpus (5)

• Doping dependence of the Fermi surface in Bi(Pb)2212
• Superconducting gap in the presence of bilayer splitting in underdoped Bi(Pb)2212
• Dynamical Screening and Superconducting State in Intercalated Layered Metallochloronitrides
• Dispersion Anomalies in Bilayer Cuprates and the Odd Symmetry of the Magnetic Resonance
• Temperature dependence of the collective mode and its influence on the band splitting in bilayer cuprates

Cited by in corpus (2)

• Phonon-assisted phase separation in strongly correlated systems
• Condensation energy of the homogeneous electron gas from the density functional theory for superconductors