2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 5: Starkey Intl. Symp. / Mineral Processing
| Editors: | Kongoli F, Kumar P, Senchenko A, Klein B, Silva A.C., Sun C, Mingan W |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 270 pages |
| ISBN: | 978-1-987820-44-7 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Towards an atomic-level understanding of the magnetic properties of materials using electron microscopy
Rafal Dunin-Borkowski1;1FORSCHUNGSZENTRUM JüLICH, Jülich, Germany (Deutschland);
Type of Paper: General Plenary
Id Paper: 436
Topic: 42
Abstract:
Transmission electron microscopy has been revolutionised in recent years, both by the introduction of new hardware such as 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. In this talk, I will describe how recent developments in transmission electron microscopy have improved our ability to obtain quantitative information about the magnetic properties of materials at close to the atomic scale. In particular, I will explain how the technique of off-axis electron holography can be used to record local variations in magnetic induction in nanoscale materials as a function of temperature and applied magnetic field in situ in the electron microscope. I will present examples of the high spatial resolution magnetic characterization of isolated and closely-spaced nanocrystals, metallic alloys and working spintronic devices examined in situ in the electron microscope. This work has benefited from the development of a model-based approach that can be used to reconstruct the three-dimensional magnetization distribution in a specimen from holograms recorded as a function of specimen tilt angle. The approach avoids many of the artifacts that result from the use of backprojection-based tomographic techniques, as well as allowing additional constraints and physical laws to be taken into account. I will also describe the application of combined chromatic and spherical aberration correction of the Lorentz lens of a transmission electron microscope to achieve magnetic-field-free imaging with the conventional microscope objective lens switched off with a spatial resolution of better than 0.5 nm. I will conclude with a personal perspective on directions for the future development of transmission electron microscopy instrumentation and techniques. When combined with advances in specimen preparation and automated image acquisition, such developments may lead to approaches for characterizing the positions, chemical identities, magnetic moments and electrostatic potentials of individual atoms in three dimensions.