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Many important properties of thin film nanomaterials are determined by the unique features of the surface and interface atoms and from interference effects due to quantum confinement. The ability to understand the detailed characteristics of the interfaces is therefore of great importance. Using a combination of experiment and theory we propose1) a non-destructive technique based on interface core level shifts to characterize the interface quality of thin film nanomaterials. The method utilizes the unique capabilities of chemical shifts of core level binding energies to probe layer resolved binary alloy composition profiles A1c(n)Bc(n) at a deeply embedded A/B interface. From an analysis based on high energy X-ray photoemission spectroscopy and density functional theory of a Ni/CuN/Ni fcc (100) model system we demonstrate that this technique is a sensitive tool to characterize the sharpness of a buried interface. To exemplify modifications of the layered structure we perform controlled interface tuning by gradually approaching the diffusion temperature of the multilayer which leads to intermixing. We show that core level spectroscopy directly reflects the changes in the electronic structure of the buried interfaces which ultimatel determines the functionality of the nano-sized material.
Almost a century ago, it was discovered that 13 percent or more chromium renders iron-chromium steels an excellent corrosion resistance, while below this threshold the alloy behaves almost like pure iron. This commonplace and most beneficial phenomenon has remained an unresolved puzzle. Here2), using first principles quantum-mechanical theory we show that this behaviour appears as a consequence of competing magnetic effects.
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