Hole-Pairs in a Spin Liquid: Influence of Electrostatic Hole-Hole Repulsion

TL;DR

This study investigates how electrostatic repulsion affects hole pairing in a spin-liquid background within the t-J model, revealing robustness of pairs under realistic Coulomb interactions and implications for high-temperature superconductivity.

Contribution

It demonstrates that hole pairs in the t-J model remain stable under significant Coulomb repulsion, providing insights into pairing mechanisms in spin-liquid systems.

Findings

Hole pairs are robust against NN Coulomb repulsion up to several times J.

Pair correlations remain strong in the regime of hole binding.

Implications for hole pairing in two-dimensional systems like copper-oxides.

Abstract

The stability of hole bound states in the t-J model including short-range Coulomb interactions is analyzed using computational techniques on ladders with up to $2 \times 30$ sites. For a nearest-neighbors (NN) hole-hole repulsion, the two-holes bound state is surprisingly robust and breaks only when the repulsion is several times the exchange $J$. At $\sim 10%$ hole doping the pairs break only for a NN-repulsion as large as $V \sim 4J$. Pair-pair correlations remain robust in the regime of hole binding. The results support electronic hole-pairing mechanisms on ladders based on holes moving in spin-liquid backgrounds. Implications in two dimensions are also presented. The need for better estimations of the range and strength of the Coulomb interaction in copper-oxides is remarked.