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Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 16: Focus Session: Oxide Semiconductors for Novel Devices III

HL 16.6: Vortrag

Dienstag, 2. April 2019, 10:45–11:00, H34

Structural, electronic and magnetic properties of Iron doped hexagonal BaTiO3: First principles investigation — •Waheed A. Adeagbo1, Sanjeev K. Nayak2, Hichem B. Hamed1, Hans T. Langhammer3, Rolf Böttcher4, and Wolfram Hergert11Institute of Physics, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany — 2Department of Materials Science and Engineering, University of Connecticut, USA — 3Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany — 4Faculty of Physics and Earth Sciences, Leipzig University, Germany

DFT calculations of Fe-doped hexagonal BaTiO3 resulted in three different Fe3+ defects incorporated at Ti sites: Two isolated defects and one associate of Fe3+ with a neighbouring oxygen vacancy. Substitution of Fe at Ti sites leads to a distortion of the surrounding oxygen octahedron. Fe is considered in different charge states. These charge states affect the Fe-O bonds and overall geometry near the defect and also influence the stability. The calculated formation energies, which are measure of the relative stability are in agreement with EPR experiment and demonstrate that Fe in BTO must exist in oxidation state of 3+ and has to occupy a face-sharing Ti(2) site while compensated by VO located in its first coordination sphere. Magnetic configurations of Fe pairs for all possible crystallographic nearest neighbor sites are also studied by calculations of the exchange interactions. A ferromagnetic coupling for the closest Fe pair is predicted and their formation is stabilized by VO. Achieving ferromagnetism in this material through impurity doping is a promising direction for further research.

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