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With nearly complete spin polarization, the ferromagnetic semiconductor europium monoxide could enable next-generation spintronic devices by providing efficient ohmic spin injection into silicon. Spin injection is greatly affected by the quality of the interface between the injector and silicon. Here, we use atomic-resolution scanning transmission electron microscopy in conjunction with electron energy loss spectroscopy to directly image and chemically characterize a series of EuO|Si and EuO|YAlO3 interfaces fabricated using different growth conditions. We identify the presence of europium silicides and regions of disorder at the EuO|Si interfaces, imperfections that could significantly reduce spin injection efficiencies via spin-flip scattering. [ABSTRACT FROM AUTHOR]

The ability to detect individual impurity atoms has been greatly enhanced by the development of aberration-corrected electron microscopes. The reduced depth of focus potentially enables three-dimensional reconstructions of impurity atoms from through-focal series. We test the robustness of this depth-sectioning method for detecting impurity atoms in gate oxides using multislice simulations. For amorphous materials, dopants can be reliably imaged, and are accurately described by a simpler three-dimensional linear imaging model. For crystalline materials, however, channeling artifacts can render the signal uninterpretable. These artifacts can be eliminated by orienting the crystal slightly off the zone axis, which still preserves atomic resolution. [ABSTRACT FROM AUTHOR]

Electron energy loss spectroscopy on an aberration-corrected scanning transmission electron microscope was used to map the elemental composition and bonding in a thin film of the multiferroic LuFe2O4 with atomic resolution. A two-dimensional analysis of the fine structure of the O-K edge yielded distinct signals for the two inequivalent oxygen sites in the crystal. Comparison to an ab-initio simulation showed that these two components can be interpreted in terms of the differing hybridization of the O p orbitals to the Lu and Fe d orbitals, thus producing an atomic-resolution map of the local oxygen bonding environment. [ABSTRACT FROM AUTHOR]