Spin Gap and Superconductivity in the One-Dimensional t-J Model with Coulomb Repulsion

TL;DR

This study explores how short-range and long-range Coulomb repulsions influence spin gaps and superconductivity in the one-dimensional t-J model, revealing that short-range repulsion enhances superconducting correlations while long-range repulsion suppresses them.

Contribution

It provides a detailed analysis of Coulomb interaction effects on superconductivity and phase separation in the 1D t-J model using exact diagonalization and quantum Monte Carlo methods.

Findings

Short-range repulsion widens the precursor region with spin gap and superconducting correlations.

Long-range $1/r$-form repulsion suppresses superconductivity.

Phase separation occurs at larger J/t with increased short-range repulsion.

Abstract

The one-dimensional t-J model with density-density repulsive interactions is investigated using exact diagonalization and quantum Monte Carlo methods. A short-range repulsion pushes phase separation to larger values of J/t, and leads to a widened precursor region in which a spin gap and strengthened superconducting correlations appear. The correlation exponent is calculated. On the contrary, a long-range repulsion of $1/r$-form suppresses superconductivity in the precursor region.