The desire to create functional materials for specific applications motivates much of today’s research in materials sciences and condensed-matter physics. Because solid-solid interfaces often exhibit properties that are foreign to the constituent materials, they can be seen as building blocks that allow us to create materials without bulk analogs. This is particularly true for transition-metal oxides in which crystal structure and electronic structure (orbital order, spin alignment, charge distribution) are strongly linked. These materials exhibit a broad range of properties related to electronic correlations, including magnetoresistance, multiferroicity, and superconductivity, and show potential for use in future energy conversion and storage approaches (photovoltaics, thermoelectrics, batteries, capacitors, etc.).
ORNL’s research emphasizes a basic understanding of interfacial properties in complex oxide materials using a combination of theoretical and experimental approaches. This work relies on the synthesis of highest-quality epitaxial structures and the use of specialized characterization techniques. For example, scanning transmission electron microscopy combined with electron energy loss spectroscopy (EELS) probes the positions as well as electronic states of individual atomic columns, while polarized neutron reflectometry resolves magnetization at the level of a single plane of spins.
Of particular interest are recent studies that emphasize the coherence of structural distortions across an interface, the intimate link between strain, vacancy formation, and ionic transport, as well as surface reconstructions and chemical activities. In fact, a free surface of a complex-oxide is a specific case of an oxide interface, which can be investigated with a variety of scanning probes and other surface-sensitive techniques.
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