Rafal Dunin-Borkowski is Director of the Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons in Forschungszentrum Jülich, Germany. He specializes in the characterization of magnetic and electronic materials at the highest spatial resolution using advanced transmission electron microscopy techniques, including aberration-corrected high-resolution transmission electron microscopy and off-axis electron holography. In 2009 he was awarded the Ernst Ruska Prize of the German Society for Electron Microscopy. In 2012, 2017 and 2019 he was awarded Advanced, Proof of Concept and Synergy Grants by the European Research Council. He has published more than 970 journal papers, conference papers and book chapters, has given more than 375 invited lectures and seminars and has received 20 prizes for papers presented at conferences and 6 prizes for science as art. 24The transmission electron microscope is a powerful tool for measuring not only local variations in microstructure and composition in materials, but also functional properties and dynamic processes. In particular, electron optical phase measurement techniques such as off-axis electron holography and electron ptychography can be used to record local variations in magnetic field and electrostatic potential within and outside materials with nm to atomic spatial resolution. In this talk, I will illustrate how such measurements, which can be made in the presence of external stimuli such as applied voltage, magnetic field, reduced or elevated temperature, reactive gas and light, can be used to provide unique information about microstructure-property relationships in nanoscale and nanostructured magnetic materials. The examples that I will present include: a) studies of magnetic moments in nanoscale spintronic devices of confined geometry that contain magnetic solitons; b) measurements of local variations in Curie temperature in layered oxides; c) highly complex magnetic behaviour resulting from hierarchical phase separation in multicomponent magnetic high entropy alloys. Quantitative analysis of the results is enabled by the application of a model-based iterative reconstruction algorithm, which can be used to retrieve the projected in-plane magnetization distribution from the magnetic contribution to a recorded electron optical phase image, or alternatively the three-dimensional magnetization distribution from a set of at least two tilt series of magnetic phase images. The technique is based on the optimized implementation of a forward model, which maps a given magnetization distribution onto one or more phase images, as well as on the use of a priori information about the positions and sizes of magnetic objects in the field of view. I will conclude with a brief description of plans for next-generation electron microscopes in the Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons in Forschungszentrum Jülich and plans for a European Distributed Research Infrastructure for Advanced Electron Microscopy. Director, Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Germany Abstract Invited Talk: S1-1Advanced Transmission Electron Microscopy of Microstructure-property Relationships in Magnetic Materials Rafal E. Dunin-Borkowski
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