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| Japanese Researchers Achieve Unprecedented Atomic-Scale Magnetic Field Resolution with Holography Electron Microscopy |
A collaborative team of Japanese researchers, including scientists from Hitachi, has achieved a record-breaking resolution of 0.47 nm in visualizing magnetic fields at the atomic scale using holography electron microscopy. This breakthrough is a significant advancement in materials science and various applied fields, made possible by new image acquisition techniques and defocusing correction algorithms.
Electron holography microscopy, a sophisticated method for visualizing magnetic fields in materials at atomic resolution, has been pushed to new limits by a team from Hitachi, Kyushu University, RIKEN, HREM Research Inc., the National Institute of Advanced Industrial Science and Technology (AIST), and the National Institute for Materials Science (NIMS). They achieved a resolution of 0.47 nm when imaging magnetic atomic lattices in a crystal, surpassing the previous record of 0.67 nm set by Hitachi in 2017.
High-performance materials with tailored properties are crucial for advancements in electronics, catalysis, transportation, and energy generation. The arrangement of atoms and the behavior of electrons within these materials determine their characteristics. Understanding the magnetic fields at the interfaces between different materials or atomic layers is essential for explaining various physical phenomena.
The research team overcame significant limitations of existing holography electron microscopes by developing an automated system to control and tune the device during data acquisition. This innovation allowed the rapid collection of 10,000 images over 8.5 hours, minimizing noise through specific averaging operations and resulting in clearer images with distinct electric and magnetic field data.
A major challenge was correcting minute defocusing that caused image aberrations. Chief Researcher Toshiaki Tanigaki from Hitachi explained, “The idea of post-image-capture correction of aberrations we employed is exactly the same as that which had motivated Dr. Dennis Gabor to invent electron holography in 1948. Until now, however, there had been no technological implementations for such automated correction in off-axis electron holography.”
This approach enabled defocusing correction due to minor focus shifts, producing images free of residual aberrations and revealing atomic positions and phases. Utilizing these innovations, the team conducted electron holography measurements on samples of Ba2FeMoO6, a layered crystalline material with distinct magnetic fields in adjacent atomic layers. Their experimental results, confirmed through simulations, set a new record by achieving a resolution of 0.47 nm.
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| Electron holography measurements on samples of Ba2FeMoO6, a layered crystalline material with distinct magnetic fields in adjacent atomic layers Image credit: Phys.org |
Tanigaki commented, “This result opens doors to direct observations of the magnetic lattices in specific areas, such as interfaces and grain boundaries, in many materials and devices. Our study marks the first step towards investigating many veiled phenomena whose existence can be revealed by electron spin configurations in magnetic materials.”
He concluded by looking toward future possibilities, stating, “Our atomic-resolution holography electron microscope will be used by various parties, contributing to advances in a wide range of fields ranging from fundamental physics to next-generation devices. Ultimately, this would pave the way for the realization of a carbon-neutral society through the development of high-performance magnets and highly functional materials that are essential for decarbonization and energy-saving efforts.”
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