Dresden 2020 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: TEM-based Nanoanalysis and Microstructure of thin films (joint session KFM/CPP)

KFM 14.1: Talk

Thursday, March 19, 2020, 14:10–14:30, HSZ 301

The effect of dynamical scattering in ferroelectrics on the measurements of internal electric fields by momentum-resolvedSTEM — •Achim Strauch^1,2, Andreas Rosenauer³, Andrei Sokolov⁴, Evgeny Tsymbal⁴, and Knut Müller-Caspary^1,2 — ¹Forschungszentrum Jülich — ²RWTH Aachen University — ³IFP Universität Bremen — ⁴University of Nebraska-Lincoln

Ferroelectric tunnel junctions (FTJs) are one focus of next-generation memories. With these non-volatile memories, the energy consumption can be reduced. Devices with BaTiO₃ tunnel junctions cannot be reversibly polarised at ferroelectric thickness below approximately 3 nm [1]. For investigations, a STEM method would be desirable to map the ferroelectric domain structure in ferroelectric nanofilms exploiting the recently accessible four-dimensional data sets from momentum-resolved STEM [2]. In this contribution, we address the impact of systematic errors arising from dynamical scattering, violated inversion symmetry, sample tilt, and redistributions of electrons due to chemical bonding in a simulation study accompanied by experiments on BaTiO₃ and PbZr_xTi_1−xO₃. The effects of dynamical scattering can lead, depending on thickness, to a systematic error [3] in the order of the expected unit-cell averaged electric fields. Finally the influence of surfaces charges will be discussed.
[1] Garcia et al., Nature Comm. 5, 4289 (2014)
[2] K. Müller et al., Nature Commun. 5, 5653 (2014)
[3] K. Müller et al., Phys. Rev. Lett. 122 (2019)