Hitachi achieves unprecedented resolution in electron holography microscopy

New advancements in image acquisition and defocusing correction techniques push the limits of atomic-scale magnetic field visualization

Image for representational purpose only!
New Delhi: A collaborative research team led by Hitachi, Ltd. has shattered previous records in the observation of atomic-scale magnetic fields using electron holography microscopy. This breakthrough, recently published in the journal Nature, marks a significant advancement in materials science with potential implications for electronics, energy generation, and beyond.
The team, comprising scientists from Hitachi, Kyushu University, RIKEN, and HREM Research Inc., partnered with the National Institute of Advanced Industrial Science and Technology (AIST) and the National Institute for Materials Science (NIMS) to enhance Hitachi’s atomic-resolution holography electron microscope. By integrating new image acquisition technology and defocus correction algorithms, they achieved a resolution of 0.47 nanometers when imaging magnetic atomic lattices within crystalline structures.
Many advances in electronic devices, catalysis, transportation, and energy generation have been facilitated by the development of high-performance materials with tailored characteristics. Before this advancement, the highest resolution for observing atomic magnetic fields was approximately 0.67 nm, achieved by Hitachi in 2017 with their advanced holography electron microscope. The team have surpassed this threshold, enabling them to discern magnetic field characteristics at an unprecedented scale.
The breakthrough was facilitated by innovations in automating device control during data acquisition, allowing for the rapid capture of 10,000 images over 8.5 hours. Through meticulous averaging and noise reduction techniques, the team produced clearer images that distinctly delineate electric and magnetic field data.
A critical challenge addressed was the correction of minute defocusing issues that previously hindered image clarity. “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. In other words, the methodology was already theoretically established. Until now, however, there had been no technological implementations for such automated correction in off-axis electron holography,” explained Chief Researcher Toshiaki Tanigaki from Hitachi, Ltd. The technique successfully corrected defocusing caused by minor shifts in focus by analyzing reconstructed electron waves. This approach resulted in images devoid of residual aberrations, allowing for clear discernment of the positions and phases of atoms along with their magnetic fields.
The research culminated in successful electron holography measurements on samples of Ba2FeMoO6, a layered crystalline material known for its distinct magnetic properties across atomic layers. By comparing experimental results with simulations, the team confirmed their achievement of observing magnetic fields at the unprecedented resolution of 0.47 nanometers.
“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,” comments an excited Tanigaki. “Our study marks the first step towards investigating many veiled phenomena whose existence can be revealed by electron spin configurations in magnetic materials.”
Looking forward, the team anticipates broader applications across scientific and technological domains. “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,” concludes Tanigaki.