November 16, 2018 - 3:00pm
Electromagnetic field mapping at the nanoscale in the transmission electron microscope
Rafal E. Dunin-Borkowski
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Germany
Transmission electron microscopy has been revolutionized in recent years, both by the introduction of new hardware such field-emission electron guns, aberration correctors and in situ stages and by the development of new techniques, algorithms and software that take advantage of increased computational speed and the ability to control and automate modern electron microscopes. These developments have resulted in the ability to provide direct images of the internal structures of materials with a spatial resolution of better than 50 pm. In this talk, I will describe how electron microscopy can be used to obtain quantitative information about not only local microstructure and chemistry in materials but also magnetic fields and charge density distributions with close-to-atomic spatial resolution. When combined with model-based iterative reconstruction, electron tomography and in situ techniques, this information can be obtained quantitatively, in three dimensions, as a function of temperature and in the presence of applied fields and reactive gases. I will present results obtained from materials that include individual magnetic nanocrystals and skyrmions in extended films and geometrically-confined structures. I will conclude with a personal perspective on directions for the future development of transmission electron microscopy, which may require radical changes to the design of electron microscopes, longer experiments, quantitative comparisons of experimental measurements with both complementary techniques and advanced simulations, and new approaches for data handling and storage.
Rafal Dunin-Borkowski is Director of the Institute for Microstructure Research and the Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons in Forschungszentrum Jülich. Between 2007 and 2010, he was Director of the Center for Electron Nanoscopy in the Technical University of Denmark. From 2000 to 2006 he held a Royal Society University Research Fellowship in the University of Cambridge. 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 of interfaces, surfaces and defects in materials, quantitative image analysis in electron microscopy for determining local compositions and site occupancies, electron tomography for determining three-dimensional morphologies and defect distributions and off-axis electron holography for characterizing magnetic and electric fields in materials with nm spatial resolution. In 2009 he was awarded the Ernst Ruska Prize of the German Society for Electron Microscopy. In 2012 he was awarded an Advanced Grant by the European Research Council.