Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 55: Multiferroic Oxide Thin Films and Heterostructures I (joint session KFM/TT/MA)
TT 55.6: Vortrag
Mittwoch, 14. März 2018, 11:00–11:15, EMH 225
Surface reconstructions and related local properties of a BiFeO3 thin film — •Pengxiang Xu1 and Lei Jin2 — 1Institute for Theoretical Physics, ETH Zurich — 2Peter Grünberg Institute (PGI-5), Forschungszentrum Juelich
Coupling between lattice and order parameters, such as polarization in ferroelectrics and/or polarity in polar structures, has a strong impact on surface relaxation and reconstruction. However, up to now, surface structures that involve the termination of both matrix polarization and polar atomic planes have received little attention, particularly on the atomic scale. Here, we study surface structures on a BiFeO3 thin film using atomic-resolution scanning transmission electron microscopy and spectroscopy. Two types of surface structure are found, depending on the polarisation of the underlying ferroelectric domain. On domains that have an upward polarisation component, a layer with an Aurivillius-Bi2O2-like structural unit is observed. Dramatic changes in local properties are measured directly below the surface layer. On domains that have a downward polarisation component, no reconstructions are visible. Calculations based on ab initio density functional theory reproduce the results and are used to interpret the formation of the surface structures.