Quantum Monte Carlo Evidence for d-wave Pairing in the 2D Hubbard Model at a van Hove Singularity

TL;DR

This study uses Quantum Monte Carlo simulations to investigate the 2D Hubbard model near a van Hove singularity, revealing a strong tendency toward d-wave pairing consistent with high-temperature superconductivity.

Contribution

It provides the first detailed Quantum Monte Carlo evidence for d-wave pairing in the 2D Hubbard model at a van Hove singularity, with implications for understanding high-Tc superconductors.

Findings

D-wave pairing tendency observed in the model.

Effective pairing interaction close to that needed for 40 K superconductivity.

Finite-size scaling aligns with results from the attractive Hubbard model.

Abstract

We implement a Quantum Monte Carlo calculation for a repulsive Hubbard model with nearest and next-nearest neighbor hopping interactions on clusters up to 12x12. A parameter region where the Fermi level lies close to the van Hove singularity at the Saddle Points in the bulk band structure is investigated. A pairing tendency in the $d_{x^2-y^2}$ symmetry channel, but no other channel, is found. Estimates of the effective pairing interaction show that it is close to the value required for a 40 K superconductor. Finite-size scaling compares with the attractive Hubbard model.