Momentum-space electronic structures and charge orders of the high-temperature superconductors Ca2-xNaxCuO₂Cl₂ and Bi₂Sr₂CaCu₂O8+δ

We study the electronic structure of Ca2-xNaxCuO₂Cl₂ and Bi₂Sr₂CaCu₂O8+δ samples in a wide range of doping, using angle-resolved photoemission spectroscopy, with emphasis on the Fermi surface (FS) in the near antinodal region. The “nesting wave vector,” i.e., the wave vector that connects two nearly flat pieces of the FS in the antinodal region, reveals a universal monotonic decrease in magnitude as a function of doping. Comparing our results to the charge order recently observed by scanning tunneling spectroscopy (STS), we conclude that the FS nesting and the charge order pattern seen in STS do not have a direct relationship. Therefore, the charge order likely arises due to strong-correlation physics rather than FS nesting physics