Fermi surface reconstruction in the single band doped Hubbard model

We study the validity of Luttinger's theorem in the 2D repulsive Hubbard model, the parent Hamiltonian for cuprate superconductors, as a function of doping. Using determinant quantum Monte Carlo (DQMC) simulations, we compute the single-particle spectral functions and from its zero energy contour in momentum space, obtain the Fermi surface of the interacting system. This reveals the following: (1) With only nearest neighbor hopping, there is a Lifshitz transition at a critical doping, followed by continuous deviation from the Luttinger volume as one approaches the Mott Insulating limit, with deviations being maximal at the antinodal points. We will discuss the relation between Luttinger breaking Fermi surface and the T linear resistivity in transport. (2) Inclusion of a next nearest neighbor hopping that breaks particle-hole symmetry changes the continuous Fermi surface into Fermi pockets around the hot spot regions. It is important to note that we find Fermi surface restructuring at intermediate temperatures, where there is no spontaneous symmetry breaking. Deviation from the Luttinger count is also accompanied by an anomalous change in Seebeck coefficient.