Origin and fate of the pseudogap in the doped Hubbard model

TL;DR

This study uses advanced Monte Carlo methods to explore the doped Hubbard model, revealing three regimes including a pseudogap phase, and connects finite temperature behavior with ground-state properties, advancing understanding of correlated electron systems.

Contribution

It provides a detailed finite-temperature phase diagram of the doped Hubbard model with insights into the pseudogap formation and its relation to magnetic correlations and ground-state phases.

Findings

Identification of three distinct regimes: weakly correlated metal, correlated metal, and pseudogap phase.

Pseudogap forms at both weak and strong coupling, linked to magnetic correlation length.

The pseudogap regime extrapolates to the ground-state stripe phase, connecting finite temperature and ground-state physics.

Abstract

We investigate the doped two-dimensional Hubbard model at finite temperature using controlled diagrammatic Monte Carlo calculations allowing for the computation of spectral properties in the infinite-size limit and, crucially, with arbitrary momentum resolution. We show that three distinct regimes are found as a function of doping and interaction strength, corresponding to a weakly correlated metal with properties close to those of the non-interacting system, a correlated metal with strong interaction effects including a reshaping of the Fermi surface, and a pseudogap regime at low doping in which quasiparticle excitations are selectively destroyed near the antinodal regions of momentum space. We study the physical mechanism leading to the pseudogap and show that it forms both at weak coupling when the magnetic correlation length is large and at strong coupling when it is shorter. In both cases, we show that spin-fluctuation theory can be modified in order to account for the behavior of the non-local component of the self-energy. We discuss the fate of the pseudogap as temperature goes to zero and show that, remarkably, this regime extrapolates precisely to the ordered stripe phase found by ground-state methods. This handshake between finite temperature and ground-state results significantly advances the elaboration of a comprehensive picture of the physics of the doped Hubbard model.