Pairing Mechanism in Two Hubbard Models that Show d_{x^2-y^2} Pairing

TL;DR

This paper investigates the pairing mechanisms responsible for d_{x^2-y^2} symmetry in two related Hubbard models, revealing how different ground states influence pairing despite similar correlations.

Contribution

It provides a comparative analysis of the pairing mechanisms in 2D and ladder Hubbard models, highlighting the role of their distinct ground states in d_{x^2-y^2} pairing.

Findings

Both models exhibit d_{x^2-y^2} pairing correlations.

The 2D model has long-range antiferromagnetic order.

The ladder model features a spin gap in its ground state.

Abstract

Here we examine various aspects of the pairing mechanism for two models, the two-dimensional and two-leg ladder Hubbard models. Both of these models exhibit pairing correlations with d_{x^2-y^2} symmetry. However, the undoped insulating states of these two systems are different with the two-dimensional lattice characterized by a ground state with long-range antiferromagnetic order and the two-leg ladder having a spin gap in its ground state. Our aim is to gain a better understanding of the underlying pairing mechanism which causes d_{x^2-y^2} pairing in these two models.