Origin and fate of the pseudogap in the doped Hubbard model

• Published in: Science (American Association for the Advancement of Science) Vol. 385; no. 6715; p. eade9194
• Main Authors: Šimkovic, Fedor, Rossi, Riccardo, Georges, Antoine, Ferrero, Michel
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 20.09.2024; American Association for the Advancement of Science (AAAS)
• Subjects: Algorithms; Antiferromagnetism; Bilayers; Brillouin zones; Climate; Computer applications; Correlation; Coupling; Density; Electron spin; Electrons; Energy charge; Exact solutions; Excitation; Fermi surfaces; Fluctuation theory; Functional materials; Graphene; Insulators; Low temperature; Magnetism; Mathematical models; Mean field theory; Metal-insulator transition; Metals; Monte Carlo Methods; Monte Carlo simulation; Nearest-neighbor; Numerical methods; Optical lattices; Parameter identification; Particle spin; Physics; Questions; Superconductivity; Temperature; Strongly Correlated Electrons; Hubbard model; Pseudogap
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.ade9194

The relationship between the pseudogap and underlying ground-state phases has not yet been rigorously established. We investigated 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 with arbitrary momentum resolution. We found three distinct regimes as a function of doping and interaction strength: a weakly correlated metal, a correlated metal with strong interaction effects, and a pseudogap regime at low doping. We show that the pseudogap forms both at weak coupling, when the magnetic correlation length is large, and at strong coupling, when it is shorter. As the temperature goes to zero, the pseudogap regime extrapolates precisely to the ordered stripe phase found by ground-state methods. Despite its simplicity, the Hubbard model may be capable of describing some instances of strongly correlated matter. However, this remains difficult to solve numerically; connecting the results at zero and finite temperatures is particularly tricky. Simkovic et al . used diagrammatic Monte Carlo calculations to examine the appearance of the pseudogap phase in the doped Hubbard model at finite temperatures. This phase was found to be closely associated with antiferromagnetic spin correlations and to connect to the ground-state stripe phase calculated at zero temperature. —Jelena Stajic