Atomic-layer-resolved composition and electronic structure of the cuprate $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{r}}_{2}\mathrm{CaC}{\mathrm{u}}_{2}{\mathrm{O}}_{8+\delta}$ from soft x-ray standing-wave photoemission

• Published in: Physical review. B 2018, Vol.98 (15)
• Main Authors: Kuo, Cheng-Tai, Lin, Shih-Chieh, Conti, Giuseppina, Pi, Shu-Ting, Moreschini, Luca, Bostwick, Aaron, Meyer-Ilse, Julia, Gullikson, Eric, Kortright, Jeffrey B., Nemšák, Slavomír, Rault, Julien E., Le Fèvre, Patrick, Bertran, François, Santander-Syro, Andrés F., Vartanyants, Ivan A., Pickett, Warren E., Saint-Martin, Romuald, Taleb-Ibrahimi, Amina, Fadley, Charles S.
• Format: Article
• Language: English
• Subjects: General Physics; Physics
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.98.155133

A major remaining challenge in the superconducting cuprates is the unambiguous differentiation of the composition and electronic structure of the Cu O 2 layers and those of the intermediate layers. The large c axis for these materials permits employing soft x-ray (930.3 eV) standing wave (SW) excitation in photoemission that yields atomic layer-by-layer depth resolution of these properties. Applying SW photoemission to B i 2 S r 2 CaC u 2 O 8 + δ yields the depth distribution of atomic composition and the layer-resolved densities of states. We detect significant Ca presence in the SrO layers and oxygen bonding to three different cations. The layer-resolved valence electronic structure is found to be strongly influenced by the atomic supermodulation structure, as determined by comparison to density functional theory calculations, by Ca-Sr intermixing, and by correlation effects associated with the Cu 3 d − 3 d Coulomb interaction, further clarifying the complex interactions in this prototypical cuprate. Measurements of this type for other quasi-two-dimensional materials with large c represent a promising future direction.