Electronic Theory for Bilayer-Effects in High-T_c Superconductors

TL;DR

This paper investigates the electronic properties of bilayer high-T_c superconductors using advanced theoretical models, revealing antiferromagnetic correlations, renormalized inter-layer hopping, and a d-wave superconducting order with inter-layer effects.

Contribution

It introduces a comprehensive theoretical analysis of bilayer high-T_c superconductors using the Hubbard model, FLEX approximation, and Eliashberg theory, highlighting inter-layer effects and symmetry of the order parameter.

Findings

Enhanced shadow band formation due to antiferromagnetic correlations.

Renormalization of inter-layer hopping suppresses inter-plane quasiparticle transfer at low doping.

Superconducting order parameter exhibits d_{x^2-y^2} symmetry with inter-layer contributions.

Abstract

The normal and the superconducting state of two coupled CuO_2 layers in the High-T_c superconductors are investigated by using the bilayer Hubbard model, the FLEX approximation on the real frequency axis and the Eliashberg theory. We find that the planes are antiferromagnetically correlated which leads to a strongly enhanced shadow band formation. Furthermore, the inter-layer hopping is renormalized which causes a blocking of the quasi particle inter-plane transfer for low doping concentrations. Finally, the superconducting order parameter is found to have a d_{x^2-y^2} symmetry with significant additional inter-layer contributions.