The Doped Two Chain Hubbard Model

TL;DR

This paper investigates the doped two-chain Hubbard model, revealing the disappearance of the charge gap, the persistence of a spin gap, and the enhancement of pairing correlations influenced by Coulomb interaction U.

Contribution

It provides new insights into the interplay between doping, spin gaps, and pairing correlations in the two-chain Hubbard model.

Findings

Charge gap vanishes upon doping

Finite spin gap persists over certain interchain hopping ranges

Pairing correlations are enhanced by onsite Coulomb interaction U

Abstract

The properties of the two-chain Hubbard Model doped away from half-filling are investigated. The charge gap is found to vanish, but a finite spin gap exists over a range of interchain hopping strength $t_\perp$. In this range, there are modified $d_{x^2-y^2}$--like pairing correlations whose strength is correlated with the size of the spin gap. It is found that the pair field correlations are enhanced by the onsite Coulomb interaction U.