| Feb 09, 2022 |
The power of seeing magnetic fields - all the way down to the atomic level
(Nanowerk News) Being able to ‘see’ magnetic fields all the way down to the atomic scale helps us better understand magnetic properties of materials.
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Such insight may help us design smaller and more efficient microelectronic devices that use magnetic properties.
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In a study published in Nature ("Real-space visualization of intrinsic magnetic fields of an antiferromagnet"), researchers from the scientific instrument manufacturer JEOL Ltd., Monash University and the University of Tokyo imaged the average magnetic fields around atomic columns in an antiferromagnet.
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“Some atoms have their own magnetic field, just like the earth has a magnetic field,” said study co-author Dr Scott Findlay, a Future Fellow at the Monash School of Physics and Astronomy.
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“The properties of a solid made of many such atoms depend on how these magnetic fields interact,” he said.
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In ferromagnets (for example, fridge magnets) the atomic magnetic fields are aligned. But other magnetic structures exist.
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In an antiferromagnet, adjacent atomic magnetic fields are oppositely directed – like a chess board where adjacent squares are opposite colours – and this is what the researchers saw.
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Imaging atoms via their electric fields has long been possible in electron microscopes. But magnetic fields are much weaker and so much harder to image.
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Study senior author Professor Naoya Shibata from the University of Tokyo said the work required overcoming three major challenges.
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“First, we needed a microscope able to image atoms in a solid without affecting the magnetic structure we’re trying to observe,” Professor Shibata said.
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“Second, we needed high signal-strength images to make the very weak magnetic fields detectable, and third, we needed a way to distinguish magnetic from electric effects,” he said. |
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In achieving this, the research used some expected properties of the antiferromagnetic structure.
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Dr Findlay said further work was needed to make this technique more general.
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