Influence of oxygen orbitals and boundary conditions on the pairing behavior in the Emery model for doped ladders

TL;DR

This study uses DMRG to analyze how oxygen orbitals and boundary conditions influence pairing in the Emery model for doped ladders, supporting potential superconductivity in hole-doped 2D cuprates.

Contribution

It demonstrates that ladder properties and pairing behavior are highly sensitive to model parameters, boundary conditions, and oxygen orbitals, providing insights into superconductivity mechanisms.

Findings

Luther-Emery phase with enhanced pairing correlations identified

Pair binding energy is more reliable than correlation functions for pairing analysis

Results support the possibility of superconductivity in hole-doped 2D cuprates

Abstract

We investigate the Emery model on several ladder-like lattices including two legs of copper d-orbitals and various numbers of oxygen p-orbitals. Pair binding energy, pair spatial structure, density distribution, and pairing correlation functions are calculated using the density matrix renormalization group (DMRG). We show that a Luther-Emery phase with enhanced pairing correlations can be found for hole doping as well as for electron doping with realistic model parameters. Ladder properties depend sensitively on model parameters, the oxygen p-orbitals taken into account, and boundary conditions. The pair binding energy is a more reliable quantity than correlation functions for studying pairing in ladders. Overall, our results for two-leg Emery ladders support the possibility of superconductivity in the hole-doped 2D model. The issue is rather to determine which of the various ladder structures and model parameters are appropriate to approximate the two-dimensional cuprates.