The finite-difference parquet method: Enhanced electron-paramagnon scattering opens a pseudogap

TL;DR

The paper introduces a finite-difference parquet method that improves the modeling of electron correlations, accurately capturing the pseudogap phenomenon in the Hubbard model through enhanced electron-paramagnon scattering analysis.

Contribution

It develops a nonperturbative, unbiased parquet approach that incorporates local physics and avoids divergence issues, advancing the study of strong-coupling electron systems.

Findings

Reproduces the pseudogap in the underdoped Hubbard model

Identifies a spin-fluctuation mechanism for the pseudogap

Highlights the importance of vertex corrections in electron-spin interactions

Abstract

We present the finite-difference parquet method that greatly improves the applicability and accuracy of two-particle correlation approaches to interacting electron systems. This method incorporates the nonperturbative local physics from a reference solution and builds all parquet diagrams while circumventing potentially divergent irreducible vertices. Its unbiased treatment of different fluctuations is crucial for reproducing the strong-coupling pseudogap in the underdoped Hubbard model, consistent with diagrammatic Monte Carlo calculations. We reveal a strong-coupling spin-fluctuation mechanism of the pseudogap with decisive vertex corrections that encode the enhanced, energy-dependent scattering amplitude between electrons and antiferromagnetic spin fluctuations.