Bilayer effects on the electronic spectra of doped cuprates

Abstract

A self-consistent perturbative approach has been used for investigating the effects of bilayer coupling in cuprate systems possessing two CuO₂ layers per unit cell. The strong electron correlation effects which exist in the individual CuO₂ layers are described by a t-t'-J model, and the coupling between the two intraunit cell layers is included via a layer-to-layer hopping matrix element t_⊥ and an exchange interaction J_⊥. Calculations of the electronic spectral function A(k,ω) have been made for different values of the hole concentration, temperature, and anisotropy for analyzing the appropriate conditions for the splitting of the quasiparticle peak in the normal state. It has been found that the splitting of the quasiparticle peak becomes favorable for higher values of the hole doping and higher anisotropy ratios. Calculations of the imaginary part of the self-energy Σ₁"(k,ω) have also been made. It has been found that Σ1"(k,ω) depends strongly on the momentum k and that the energy dependence of Σ"(k,ω) changes qualitatively with the change of the momentum k. For k=(0,0) a Fermi liquid like behavior is found for low ω, while for other values of momentum, considered here, Σ₁"(k,ω) varies like ω^α(1<α<2).