Berlin 2018 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 20: Multiferroic Oxide Thin Films and Heterostructures II (joint session KFM/TT/MA)

KFM 20.10: Vortrag

Mittwoch, 14. März 2018, 18:00–18:15, EMH 225

Electronic and magnetic properties of BaFeO₃-Pt(111) in a quasicrystalline approximant structure — •Waheed A. Adeagbo, Igor V. Maznichenko, Hichem Ben-Hamed, Ingrid Mertig, and Wolfram Hergert — Institute of Physics, Martin Luther University Halle-Wittenberg, Germany

The first reported formation of an oxidic quasicrystal (OQC) BaTiO₃ (BTO) on Pt(111) has led to finding of other quasicrystalline (QC) perovskites like SrTiO₃ on the same substrate. Since these are non-magnetic, it is interesting to investigate the properties of magnetic perovskites in corresponding approximant structures. BaFeO₃ (BFO) has a very good lattice match with Pt(111) and also a robust magnetic properties which could add new interesting features to the QC systems. In this work we have carried out first principles study on the periodic BFO bulk crystals properties in the cubic (c-BFO) and the hexagonal (6h-BFO) phases. The derived OQC thin film which exhibits strong similarities to the BTO-derived OQC with respect to the local tiling geometry of Kepler’s approximant was also studied both in the free standing and in the supported phase on Pt(111) surface. Our results shows that the anti-ferromagnetic 6h-BFO bulk phase is preferable ground state to c-BFO phase. Like in BTO-OQC approximant, the BFO also shows all four Fe atoms surrounded by three O atoms with the FeO₃ units separated by Barium atoms with the total stoichiometry Ba₅Fe₄O₁₀. Since the exact oxidation states of the Fe and the role of O vacancy in the stabilization is unknown for these systems, the results of these will be presented together with the magnetic contribution.