2025/04/03 by Schumm, Gabe, Zhang, Shiwei, Sandvik, Anders W. · 1 citation
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2504.02614
Implementing an improved method for analytic continuation and working with imaginary-time correlation functions computed using quantum Monte Carlo simulations, we resolve the single-particle dispersion relation and the density of states (DOS) of the two-dimensional Hubbard model at half-filling. At intermediate interactions of U/t = 4,6, we find quadratic dispersion around the gap minimum at wave-vectors k = (± π/2, ± π/2) (the Σ points). We find saddle points at k = (± π,0),(0,± π) (the X points) where the dispersion is approximately quartic, leading to a sharp DOS maximum above the almost flat ledge arising from the states close to Σ. The fraction of quasiparticle states within the ledge is n\rm ledge ≈ 0.15. Upon doping away from half-filling, within the rigid-band approximation, these results support Fermi pockets around the Σ points, with states around the X points becoming filled only at doping fractions x ≥ n\rm ledge. The high density of states away from the Σ gap edge may be an important clue for a finite minimum doping level for superconductivity and other instabilities of doped Mott insulators.