Octahedral distortions and chemistry at interfaces of oxide heterostructures
Complex oxide materials exhibit a wide range of ionic and electronic phenomena such as superconductivity, magnetism, ferroelectricity, thermoelectricity, etc. The crystal structure of oxides (generally perovskite or a derivative) is highly adaptable to changes in composition and this compatibility provides the opportunity of combining multiple oxides into heterostructures .
Oxide heterostructures show extraordinary electronic properties that do not exist in bulk forms and the emergent phenomena occurring at the interfaces of these heterostructures are fascinating where the distortions of the crystal lattice plays a crucial role . Thus, atomistic understanding of these distortions and elucidation of their influence on the final properties requires imaging and measuring of atomic positions of both cations and oxygen together with local analytical measurements. The annular bright-field (ABF) imaging technique enables simultaneous imaging of heavy and light elements and allows for simultaneous acquisition of other signals, for example electrons scattered to large angles (high-angle annular dark-field (HAADF), also called Z-contrast imaging), characteristic X-rays (energy-dispersive X-ray spectroscopy (EDXS)), and electron energy loss (EELS) .
Our aim is to reveal the atomic, chemical and electronic structure and to investigate the octahedral tilts at the interfaces of oxide heterostructures (e.g . cuprates, vanadates, nickelates etc.) via various STEM techniques such as STEM-HAADF and -ABF imaging, EELS and EDXS.
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Researchers from Dept. Keimer and Dept. Maier collaborate in present projects.