A photoemission study of the influence of sputtering on the Au-Bi(2212) interface
TL;DR: In this paper, X-ray photoemission measurements were performed on Au deposited on a Bi(2212) single crystal after progressively sputtering it with Ar ions, and the results revealed no elemental diffusion at the interface and an absence of Au interaction with the crystal at room temperature.
Abstract: X-ray photoemission measurements were performed on Au deposited on a Bi(2212) single crystal after progressively sputtering it with Ar ions. This was to see whether changes such as diffusion of Au, segregation of a particular element or clustering effects take place at the interface. Spectra of different core levels reveal no elemental diffusion at the interface and an absence of Au interaction with the crystal at room temperature.
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TL;DR: A review of photoemission measurements on high-temperature superconductors is presented in this article, providing the reader with an overview of the present status of the field and future implications.
Abstract: A review of photoemission measurements on high-temperature superconductors is presented. Earlier photoemission results and interpretations are critically examined, providing the reader with an overview of the present status of the field. Special emphasis is paid to recent progress, in particular the revelation of the superconducting gap, and angle-resolved photoemission studies of high-quality single crystals of the Bi2Sr2CaC2O8 material. Comparison with predictions of band calculations and impurity model calculations as well as the electronic structure of some transition-metal oxides is made. Finally, comments on the present status of photoemission studies of the high-temperature superconductors and future implications are given.
90 citations
TL;DR: In this paper, the core-level results show that Rb strongly reacts with the Bi and O states, while the Cu and Sr states are left unchanged, and that the Bi-O plane forms the surface layer.
Abstract: Single crystals of ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}\mathrm{Ca}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ superconductors, in situ cleaved and modified by Rb and oxygen overlayers, have been studied using ultraviolet and x-ray photoemission spectroscopy The core-level results show that Rb strongly reacts with the Bi and O states, while the Cu and Sr states are left unchanged This observation strongly indicates that the Bi-O plane forms the surface layer Subsequent exposure to oxygen results in new oxygen states at the surface as monitored by the O $1s$ core-level data For both Rb and oxygen overlayers the valence-band spectra are severely altered In particular, new valence-band states, presumably of oxygen character, are formed
41 citations
TL;DR: In this paper, photoelectron spectroscopy has been used to study the effect on the electronic structure of the Bi-Ca-Sr-Cu-O surface of Ne sputtering, deposition of Ag, and annealing in ultrahigh vacuum, aiming at gaining insight into the role of different processing parameters.
Abstract: Photoelectron spectroscopy has been utilized to study the effect on the electronic structure of the Bi‐Ca‐Sr‐Cu‐O surface of Ne sputtering, deposition of Ag, and annealing in ultrahigh vacuum, aiming at gaining insight into the role of different processing parameters. The results show that all these treatments significantly reduce the valency of Cu in the superconductor, and strongly modify the electronic states in the valence band. In addition, Ne sputtering or annealing in ultrahigh vacuum gives rise to new features in both the O 1s core‐level data and in the valence band. We conclude that the electronic structure of the Bi‐Ca‐Sr‐Cu‐O surface is very sensitive to different methods of preparation.
34 citations
TL;DR: In this paper, X-ray photoemission spectroscopy was used to examine the reactivity of clean YBa2Cu3O6.9 and Bi2Ca1+xSr2−xCu2O8+y surfaces with adatoms of vapordeposited bismuth.
Abstract: X‐ray photoemission spectroscopy was used to examine the reactivity of clean YBa2Cu3O6.9 and Bi2Ca1+xSr2−xCu2O8+y surfaces with adatoms of vapor‐deposited bismuth. For YBa2Cu3O6.9, depositions ≤8 A of Bi induce O 1s, Cu 2p3/2, and Bi 4f line‐shape changes due to BiO bonding, limited oxygen loss from the substrate, partial conversion of Cu2+ to Cu1+, and growth of Bi metal. For coverages greater than 8 A, there is no reaction and only Bi metal growth is observed. For Bi deposition onto Bi1Ca1+xSr2−xCu2O8+y, there is minimal reaction with only subtle O 1s and Cu 2p3/2 line‐shape changes and the nucleation and growth of Bi metal starting at low coverages (≥2 A). Comparison shows that Bi is less reactive than other metals, except Ag and Au, and that Bi2Ca1+xSr2−xCu2O8+y is more stable toward Bi deposition than YBa2Cu3O6.9.
34 citations
TL;DR: Core-level attenuation results suggests minimal outdiffusion of oxygen, in contrast with what is observed for Cu/YBa/sub 2/Cu/sub 3/O/sub 7-//sub x/.
Abstract: The electronic structure and surface interactions of vapor-deposited Cu on single-crystal and polycrystalline ${\mathrm{Bi}}_{2}{\mathrm{Ca}}_{1+x}{\mathrm{Sr}}_{2\ensuremath{-}x}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+y}$ were studied using x-ray photoelectron spectroscopy. The results are compared to the $\frac{\mathrm{Cu}}{\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}}$ interface. Changes in the $\mathrm{Cu} 2p$ satellite emission indicate that the Cu adatoms do not disrupt ${\mathrm{Bi}}_{2}{\mathrm{Ca}}_{1+x}{\mathrm{Sr}}_{2\ensuremath{-}x}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+y}$ as extensively as $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$. However, deposition of Cu induces changes in the Bi environment in the superconductor, and surface segregation of Bi metal was observed at high coverages. Core-level attenuation results suggest minimal out-diffusion of oxygen, in contrast with what is observed for $\frac{\mathrm{Cu}}{\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}}$.
31 citations