U-J Synergy Effect for the High Tc Superconductors

TL;DR

This paper explores how the combined effects of exchange interaction J and Coulomb repulsion U in a 2D extended Hubbard model enhance antiferromagnetic and d-wave superconducting correlations, providing insights into high Tc superconductors.

Contribution

It demonstrates that the synergy between J and U interactions significantly boosts superconducting and magnetic correlations in the model.

Findings

J and U interactions enhance d-wave superconductivity.

Antiferromagnetism is prominent near half-filling.

Synergistic effects improve understanding of high Tc mechanisms.

Abstract

Using renormalization group and exact diagonalization of small clusters we investigate the ground state phase diagram of a two-dimensional extended Hubbard model with nearest-neighbor exchange interaction J, in addition to the local Coulomb repulsion U. The main instabilities are antiferromagnetism close to half-filling and d-wave superconductivity in the doped system. Our results suggest that the combined action of J and U interactions provide a remarkably efficient mechanism to enhance both d-wave superconducting and antiferromagnetic correlations.