| Feb 27, 2025 |
A twist you’ll never see coming: a breakthrough in understanding the relationship between chirality and electric flow at a microscopic level may help us develop chiral information technology.
(Nanowerk News) Researchers at Tohoku University, the University of Manchester, and Osaka University have made a breakthrough that has the potential to ignite the development of next-gen chiral information technology.
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The findings have been published in PNAS (“Band asymmetry-driven nonreciprocal electronic transport in a helimagnetic semimetal α-EuP3“).
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| Image of the micro-fabricated device made from the chiral magnetic material α-EuP3. (Image: A. H. Mayo et al.)
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Chirality is a property of materials where their mirror image is not identical to the original–just like our left and right hands. This unique characteristic creates two distinct states, which researchers believe could one day be used to store digital information, much like the “0” and “1” states in conventional computing.
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“Among various materials, helimagnets are particularly interesting because they exhibit chirality through their magnetic structure,” says Alex Hiro Mayo (Tohoku University), “However, a major challenge in using these materials for information storage lies in how to effectively read out their chirality.”
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One promising solution comes from an unusual effect called nonreciprocal electronic transport, where electric current flows more easily in one direction than the other. This one-way electric flow, known as rectification, directly reflects the chirality of the material and could serve as a way to “read” magnetic information.
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“If we can find a way to accurately use chirality to store data, it would mean a new era for information storage devices. However, the microscopic mechanism behind this rectification effect in chiral magnets is not yet fully understood. Unraveling this mechanism is essential for establishing material design principles that enable efficient chirality detection and enhanced readout performance,” explains Mayo.
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This collaborative research project addresses this knowledge gap by focusing on a unique quantum material – α-EuP3 – which is a helimagnetic material where the local magnetic moments of europium (Eu) atoms create a chiral magnetic texture. They carefully controlled the magnetic structure using external magnetic fields, which in turn manipulated the material’s electronic behavior to reveal the microscopic origins of nonreciprocal transport.
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Unlike conventional metals with complex “electronic band structures”, which dictate how electrons flow inside a material, α-EuP3 has a simpler electronic landscape, making it an ideal platform for uncovering the direct relationship between magnetism and electron transport. By altering the material’s magnetic state between chiral and achiral phases, researchers observed a strong rectification effect in the chiral phase, which completely vanished as soon as the magnetic state transitioned to the achiral phase.
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| Relationship among the magnetic structure, electronic structure, and electron flow in the material. As a magnetic field is applied along the spiral axis, the magnetic structure deforms into a conical shape, inducing asymmetry in the electronic landscape and resulting in electron-flow rectification. Once the system becomes achiral (i.e., ferromagnetic, as shown in this figure), the rectification effect vanishes. (Image: A. H. Mayo et al.)
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Combining experimental results with theoretical calculations, they demonstrated that the “magnetic twist” in the chiral phase directly induces electronic band asymmetry, which in turn triggers one-way electric flow.
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This work provides a crucial microscopic-level understanding of how magnetic chirality governs electronic transport, offering key insights for designing new functional quantum materials and enabling future applications in chiral information storage and next-generation electronic devices.
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