Structure, Superstructure and Charge Order in Bi-Cuprates

Inhomogeneities in any form, affecting either the structural properties as superstructures or the electronic degrees of freedom as stripes, play an essential role in the unusual properties of the cuprates. Bi-cuprates, favored for photoemission studies, are unfortunately prone to structural inhomogeneity and superstructure modulations. We have therefore performed combined STM and high resolution photoemission studies on Bi_2−y Pb _y Sr_2−x La _x CuO_6+δ (Pb-Bi2201) for different compositions and identified the contributions due to superstructures beyond the well-known (1×4.7) reconstruction. Since the inclusion of the related scattering vectors gives a nearly perfect image of the experimental Fermi surface, it can be speculated how far such modeling is necessary to understand the spectral lineshape.