| Jun 08, 2023 |
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(Nanowerk News) A team of physicists, spearheaded by Professor SHAO Dingfu from the Hefei Institutes of Physical Science (HFIPS), have theoretically predicted the existence of “parallel circuits” of spin currents in antiferromagnets. This prediction, they believe, holds the potential to substantially expedite the progression of spintronics.
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The research was peer-reviewed and has been published in Physical Review Letters (“Néel Spin Currents in Antiferromagnets”).
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Spintronics represents a cutting-edge frontier in data storage and processing technology. It leverages the spin of electrons within magnetic substances to encode data. A critical component of spintronics are the spin-polarized electric currents, which command and discern magnetic moment orientations, thereby facilitating the writing and reading of binary data – the 1s and 0s.
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At the present, a majority of spintronic devices are predicated on ferromagnets due to their ability to effectively spin polarize electric currents courtesy of their net magnetizations. Antiferromagnets, despite having alternately aligned opposing magnetic moments, have been relatively less explored. However, these materials may pave the way for even more efficient, compact spintronic devices.
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One major impediment for antiferromagnets is their zero net magnetization, leading to the prevailing belief that they can only carry spin-neutral currents, which are ostensibly irrelevant for spintronics. Antiferromagnets are composed of two antiparallel aligned magnetic sublattices. Conventionally, the properties of these sublattices are thought to be “averaged out”, causing them to spin independently.
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Challenging this common notion, Professor SHAO put forth a hypothesis suggesting that collinear antiferromagnets could operate as “electrical circuits”. These circuits would comprise two magnetic sublattices functioning in parallel, given the presence of strong coupling between magnetic atoms within each sublattice. Acting on this intuition, Professor SHAO and his team provided a theoretical framework predicting that magnetic sublattices within these antiferromagnets could locally polarize the electric current. This would, in turn, generate staggered spin currents concealed within the globally spin-neutral current.
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These staggered spin currents have been christened as “Néel spin currents”, a tribute to the Nobel laureate Louis Néel, who won the prestigious accolade for his foundational work and breakthroughs in the field of antiferromagnetism.
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“The Néel spin currents represent a unique property of antiferromagnets that, until now, has remained largely unrecognized,” stated Professor SHAO. “These currents hold the potential to engender beneficial spin-dependent characteristics that were hitherto considered incompatible with antiferromagnets. For instance, they could bring about spin-transfer torque and tunneling magnetoresistance in antiferromagnetic tunnel junctions, which are essential for electrically encoding and retrieving information in antiferromagnetic spintronics.”
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