Enhancement of Pairing Correlation and Spin Gap through Suppression of Single-Particle Dispersion in One-Dimensional Models

TL;DR

This study shows that flattening the band dispersion near the Fermi level in one-dimensional models enhances the spin gap and pairing correlations, suggesting a flat-band induced pairing mechanism.

Contribution

It demonstrates how suppressing single-particle dispersion near the Fermi level enlarges the spin gap and pairing regions in strongly correlated 1D models, proposing a new flat-band pairing mechanism.

Findings

Spin gap region expands with flatter band dispersion.

Singlet-pairing correlation becomes more dominant with flatter bands.

Proposes a pairing mechanism induced by flat-band dispersion.

Abstract

We investigate the effects of suppression of single-particle dispersion near the Fermi level on the spin gap and the singlet-pairing correlation by using the exact diagonalization method for finite-size systems. We consider strongly correlated one-dimensional models, which have flat band dispersions near wave number k=\pi/2, if the interactions are switched off. Our results for strongly correlated models show that the spin gap region expands as the single-particle dispersion becomes flatter. The region where the singlet-pairing correlation is the most dominant also expands in models with flatter band dispersions. Based on our numerical results, we propose a pairing mechanism induced by the flat-band dispersion.