Superconductivity and antiferromagnetism in the two-dimensional Hubbard model: a variational study

TL;DR

This study uses a variational approach to explore superconductivity and antiferromagnetism in the 2D Hubbard model, revealing new insights into magnetic order at half filling and evidence of superconductivity away from half filling.

Contribution

It introduces a superior variational wave function for the Hubbard model, providing improved analysis of magnetic and superconducting phases.

Findings

Enhanced understanding of antiferromagnetic order at half filling.

Evidence supporting superconductivity away from half filling.

Demonstration of the variational method's effectiveness for intermediate coupling.

Abstract

A variational ground state of the repulsive Hubbard model on a square lattice is investigated numerically for an intermediate coupling strength (U = 8t) and for moderate sizes (from 6 x 6 to 10 x 10). Our ansatz is clearly superior to other widely used variational wave functions. The results for order parameters and correlation functions provide new insight for the antiferromagnetic state at half filling as well as strong evidence for a superconducting phase away from half filling.