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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 19: Topical Session: In Situ and Multimodal Microscopy in Materials Physics (joint session MM/KFM)
KFM 19.1: Topical Talk
Wednesday, March 20, 2024, 15:30–16:00, C 130
Charges, Structure, Properties - Concepts and Applications of four-dimensional electron microscopy — •Knut Müller-Caspary1,3, Benedikt Diederichs1,2, Ziria Herdegen1, Tizian Lorenzen1, Felix Dushimineza1,3, Max Leo Leidl1,3, Achim Strauch3, and Frank Filbir2 — 1Ludwig-Maximilians-Universität München, Dept. of Chemistry, Butenandtstr. 11, 81377 München — 2Institute of Biological and Medical Imaging, Helmholtz Zentrum München, 85764 Neuherberg, Germany — 3Forschungszentrum Jülich, Wilhelm Johnen Str., 52425 Jülich
Scanning an electron probe across a specimen and recording a diffraction pattern at each scan point established 4D-STEM as a versatile concept to characterise materials. We start with a very brief introduction of mapping electric fields and electrostatic potentials by using direct methods such as centre-of-mass imaging and analytical ptychographic solutions to the inverse single-scattering problem. Applications to large-scale electric field mapping and 2D materials will be shown. For thicker specimens, structure retrieval needs to invert multiple scattering. In this respect, we report a parametric inverse multislice concept in which both partial coherence of the probe and multiple frozen phonon states are taken into account. In particular, we investigate the impact of thermal diffuse scattering on different inverse multislice approaches. The concept is demonstrated via simulations first, and then applied to measure ionic displacements in ferroelectrics with picometre precision.
Keywords: Transmission electron microscopy; Ptychography; Electric fields; 2D materials; Ferroelectrics