Anisotropy on the Fermi Surface of the Two-Dimensional Hubbard Model

Abstract

We investigate anisotropic charge fluctuations in the two-dimensional Hubbard model at half filling. By the quantum Monte Carlo method, we calculate a momentum-resolved charge compressibility $κ(\bm{k}) = {d < n(\bm{k}) >}/{d μ}$, which shows effects of an infinitesimal doping. At the temperature $T \sim {t^2}/{U}$, $κ(\bm{k})$ shows peak structure at the $(\pm π/2,\pm π/2)$ points along the $|k_x| + |k_y| = π$ line. A similar peak structure is reproduced in the mean-filed calculation for the d-wave pairing state or the staggered flux state.

5 pages, 3 figures, figures and presentation are modified