Spin exchange and superconductivity in a $t-J'-V$ model for two-dimensional quarter-filled systems

TL;DR

This paper investigates how antiferromagnetic spin fluctuations and charge interactions in a two-dimensional quarter-filled system promote d$_{xy}$ pairing, revealing a cooperative effect that enhances superconductivity.

Contribution

It introduces a $t-J'-V$ model incorporating charge and spin fluctuations and demonstrates that $J'$ specifically enhances d$_{xy}$ pairing through a cooperative mechanism.

Findings

$J'$ increases attraction in the d$_{xy}$ channel.

Charge and spin fluctuations work together to promote d$_{xy}$ pairing.

The model explains the role of spin fluctuations in superconductivity at quarter filling.

Abstract

The effect of antiferromagnetic spin fluctuations on two-dimensional quarter-filled systems is studied theoretically. An effective $t-J'-V$ model on a square lattice which accounts for checkerboard charge fluctuations and next-nearest-neighbors antiferromagnetic spin fluctuations is considered. From calculations based on large-N theory on this model it is found that the exchange interaction, $J'$, increases the attraction between electrons in the d$_{xy}$ channel only, so that both charge and spin fluctuations work cooperatively to produce d$_{xy}$ pairing.