Epitaxy and electronic structure of ρ(1×1)Cr/Au(100)

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Abstract
Low-energy electron-diffraction, Auger-electron, He i photoemission, and electron-energy-loss spectroscopies were used to characterize the epitaxy and electronic structure of Cr overlayers deposited on single-crystal Au(100). Epitaxy was achieved for substrate-deposition temperatures above ∼100–150 °C. The observed strain-free p(1×1) Cr/Au(100) epitaxy is due to the fortuitous matchings of the primitive two-dimensional square nets of Cr(100) and Au(100) bulk terminations. Surface states near the Fermi energy of pure Cr(100) are found to persist at the Cr-Au interface, in agreement with recent theoretical findings. The electronic structure of Cr multilayers on Au(100) is closely related to that of ordinary bcc Cr. The results are discussed in terms of the recently reported superconducting behavior of Au/Cr/Au(100) sandwiches attributed to fcc Cr possessing the 41%-expanded lattice constant of Au. An alternate hypothesis for the sandwich superconductivity is suggested in terms of disordered Cr.