Superconductivity and Pairing Fluctuations in the Half-Filled Two-Dimensional Hubbard Model

TL;DR

This study uses advanced computational methods to explore superconductivity and pairing fluctuations in the half-filled 2D Hubbard model, revealing non-Fermi liquid behavior and the dominance of pairing fluctuations above the transition temperature.

Contribution

It demonstrates the presence of d-wave superconductivity and pairing fluctuations in the half-filled 2D Hubbard model using plaquette cluster DMFT with quantum Monte Carlo.

Findings

Non-monotonous low-frequency scattering rate near (, 0)

T-linear dc conductivity at high temperatures

Pairing fluctuations dominate above the superconducting transition

Abstract

The two-dimensional Hubbard model exhibits superconductivity with d-wave symmetry even at half-filling in the presence of next-nearest neighbor hopping. Using plaquette cluster dynamical mean-field theory with a continuous-time quantum Monte Carlo impurity solver, we reveal the non-Fermi liquid character of the metallic phase in proximity to the superconducting state. Specifically, the low-frequency scattering rate for momenta near (\pi, 0) varies non-monotonously at low temperatures, and the dc conductivity is T-linear at elevated temperatures with an upturn upon cooling. Evidence is provided that pairing fluctuations dominate the normal-conducting state even considerably above the superconducting transition temperature.