Pairing and charge distribution in Emery ladders preserving the ratio of Cu to O atoms

TL;DR

This study investigates Emery ladder models of cuprates, confirming their insulating and superconducting phases, and analyzes charge distribution and pairing correlations, providing insights consistent with experimental observations.

Contribution

It introduces Emery ladder models that preserve Cu to O ratios, enabling detailed analysis of charge distribution and pairing in cuprates.

Findings

Emery ladders are charge-transfer insulators at undoped levels.

Doped Emery ladders exhibit Luther-Emery liquid behavior with enhanced pairing.

Charge distribution correlates with pairing strength and interactions.

Abstract

We study the Emery model (three-band Hubbard model) for superconducting cuprates on three distinct ladder-like lattices that are supercell of the CuO$_2$ plane and thus preserve the ratio of copper to oxygen atoms. Using the density-matrix renormalization group method we confirm that these Emery ladders are charge-transfer insulators for the hole concentration corresponding to undoped cuprates but become Luther-Emery liquids with enhanced pairing correlations upon doping. The preservation of the Cu to O ratio allows us to study the distribution of charges between these atoms in the Luther-Emery phase. We show that these Emery ladders can describe the relations between charge distribution, pairing strength, and interactions that have been observed in the Emery model on two-dimensional clusters and in experiments.