Fermi arcs and pseudogap emerging from dimensional crossover at the Fermi surface in La2−xSrxCuO4

Abstract

The doping mechanism and realistic Fermi surface (FS) evolution of La2−xSrxCuO4 (LSCO) are modelled within an extensive ab initio framework including advanced band-unfolding techniques. We show that ordinary Kohn-Sham DFT+U can reproduce the observed metal-insulator transition, when not restricted to the paramagnetic solution space. Arcs are self-doped by orbital charge transfer within the Cu-O planes, while the introduced Sr charge is strongly localized. Arc protection and the inadequacy of the rigid-band picture are consequences of a rapid change in orbital symmetry at the Fermi energy: the material undergoes a dimensional crossover along the Fermi surface, between the nodal (2D) and antinodal (3D) regions. In LSCO, this crossover accounts for FS arcs, the antinodal pseudogap, and insulating behavior in c-axis conductivity, all ubiquitous phenomena in high-Tc cuprates. Ligand Coulomb integrals involving out-of-plane sites are principally responsible for the most striking effects observed by ARPES in LSCO.