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A3: Atomic structure and local spectroscopy of complex oxidic structures

For functionality engineering of future oxidic heterostructures the understanding of the important interface-mediated interactions are essential. In this project the interplay between local atomic structure at the interface and their local electronic respective ferroelectric structure will be studied for ultrathin films of ferroelectric and ferromagnetic oxides as CoZrO₂, CoFe₂O₄, BaTiO₃/SrTiO₃ based on various scanning probe techniques and photoelectron spectroscopy and microscopy.

For the coupling between different oxidic components the structural modifications at the interface and the modified properties as electronic structure, dielectric and magnetic moments are important. Here we will study both based on scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) at variable temperatures as well as by piezoelectric scanning force microscopy (PFM) and photoelectron microscopy (PEEM). In cooperation with theory projects we aim at a better understanding of interface-driven structure and property modifications for future use in extrinsic multiferroics. In the first funding period potentially ferromagnetic and ferroelectric oxide films will be investigated with respect to lattice mismatch, film thickness, and stochiometry deviations. A special highlight of our approach includes - besides imaging and spectroscopy at the oxide-vacuum interface - the characterization of the first inner interface by STM and STS. In addition to layered structures, lateral heterostructures will also be included as far as they are relevant for multiferroics. For lateral heterostructures the spatially resolved spectroscopies allow for far-reaching characterizations across several interfaces.

Principal Investigator

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