Atomic configuration in cuprates at the closing of the pseudogap

TL;DR

This paper investigates the atomic arrangements of oxygen atoms in different cuprate families at the pseudogap closing point, revealing symmetric configurations that influence electronic properties and phase behavior.

Contribution

It identifies and visualizes the atomic configurations of oxygen atoms at the pseudogap closing in two cuprate families, highlighting their structural differences and implications for electronic phases.

Findings

Symmetric oxygen configurations emerge at pseudogap closure.

Distinct superlattice arrangements are identified in each cuprate family.

Implications for bandstructure and strange-metal phase are discussed.

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.