Quasiparticle bands and superconductivity in bilayer cuprates

TL;DR

This paper investigates the energy spectrum and superconductivity in bilayer cuprates using a realistic extended Hubbard model, revealing unique quasiparticle features and their impact on superconducting temperature.

Contribution

It provides a detailed analysis of quasiparticle bands and superconductivity in bilayer cuprates, highlighting differences from simpler models and the effects of interlayer coupling.

Findings

Quasiparticle bands have flat regions near X(Y) points.

Van-Hove singularity is pinned to the Fermi level in bilayers.

Superconducting temperature is not reduced by bilayer hopping.

Abstract

We analyze the generic features of the energy spectrum for two coupled CuO$_2$ layers with a realistic extended Hubbard model. The quasiparticle bands exhibit flat regions near X(Y) points in the Brillouin zone with a large reduction of the bonding-antibonding splitting, and pinning of extended van-Hove singularity to the Fermi level, which is more efficient for a bi-layers than for a single layer. In contrast to the results with simpler models, the superconducting temperature for d$_{x^2-y^2}$ pairing is not lowered by the bi-layer hopping.