Atomic configuration in cuprates at the closing of the pseudogap

Abstract

Doped holes in cuprates reside pairwise at lattice-defect O atoms but at different sites in the two cuprate families. In the Sr-doped lanthanum cuprates, the O atoms occupy anion lattice sites and spread due to Coulomb repulsion (relative to the host lattice). In the oxygenated cuprates, the O atoms occupy interstitial sites, hybridize to ozone complexes, and aggregate to strings or (at high oxygenation) to nematic patches, always with spacing of ~ 3.25a_0. At the closing of the pseudogap at hole doping p*, a highly symmetric configuration of the O atoms appears in each family. In the first family it consists of interlaced superlattices in the CuO_2 plane and each of the bracketing LaO layers, with spacing A_0^{LaO}(p*) = 2A_0^{CuO_2}(p*). In the second family it consists in the completion of a 2D superlattice of ozone complexes, with spacing A_0(p*) ~ 3.25a_0. Both cases are visualized. Implications for the bandstructure and strange-metal phase are considered.