Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Ferroics – Domains and Domain Walls 1

KFM 14.6: Vortrag

Mittwoch, 7. September 2022, 11:25–11:45, H5

Electron scattering signatures of ferroelectric domains — •Ursula Ludacka1, Jiali He1, Emil Frang Christiansen1, Shuyu Qin2, Zewu Yan33, 4, Edith Bourret4, Antonius van Helvoort1, Joshua Agar2, and Dennis Meier11NTNU Norwegian University of Science and Technology, Trondheim, Norway — 2Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015, USA — 3ETH Zurich, Zurich, Switzerland — 4Lawrence Berkeley National Laboratory, Berkeley, USA

The emergence of ferroelectricity originates from polar displacements of lattice atoms, connotating a one-to-one correlation between electronic and structural properties at the atomic level. An established approach that allows for determining associated structural variations is scanning electron diffraction (SED). In SED, a focused electron beam is scanned over the specimen, probing diffracted electrons at each position of the raster scan. The corresponding patterns represent unique fingerprints of the probed areas, containing structural information. We demonstrate the potential and opportunities of this innovative 4D-STEM approach using improper ferroelectric ErMnO3, an ideal model system as its basic ferroelectric properties and atomic-scale structure are well understood. In the ferroelectric state, the Er ions exhibit characteristic up-up-down and down-down-up patterns, corresponding to ferroelectric 180 domains with positive and negative polarization, respectively. These shifts cause different Bragg scattering conditions for the electrons and, hence, specific diffraction patterns that we utilize for domain imaging assisted by machine learning algorithms.

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