Highlights

In brief

A new method using double magnetic layers to stabilise and control skyrmions without applying a magnetic field enables faster, lower-energy computing.

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Spinning wonders of future computing

7 Oct 2024

Complex magnetic particle arrangements, called skyrmions, can transform computing by making data storage and processing more efficient and energy-saving.

Nanometer-scale compass needles, known as skyrmions, are magnetic textures in certain materials. Their low-energy creation, manipulation and erasure make them ideal for future computing technologies, especially biomimetic computing.

Anjan Soumyanarayanan, a Research Scientist at A*STAR’s Institute of Materials Research and Engineering (IMRE), has been exploring the potential of skyrmions with lead author Xiaoye Chen; IMRE Lead Research Engineer, Hui Ru Tan; and other researchers at the Spin Technology for Electronic Devices (SpEED) team, as well as National University of Singapore.

Chen explained that conventional computers use transistor-based hardware to simulate neural networks for artificial intelligence tasks. Meanwhile, biomimetic computing uses specialised hardware that replicates the behaviour of biological brain cells.

"This allows a computer to natively perform neural network inference tasks without using an emulation layer, offering superior speed and efficiency compared to present-day computers," said Chen.

Despite their potential, skyrmions face stability hurdles. While they form compact structures under an external magnetic field, they become unstable and stretch into stripe-like formations when the field is removed, losing essential characteristics needed for computing applications.

To counter this, the team posited that integrating two distinct types of magnetic interactions within specially engineered magnetic layers can maintain skyrmion stability under ambient conditions without an externally applied magnetic field.

The team used wafer-scale techniques, transmission electron microscopy (TEM), and detailed simulations to tweak skyrmion behaviour in custom magnetic structures. They overcame hurdles by developing methods to quantify interlayer exchange coupling (IEC), a critical but not directly measurable parameter.

Ultrathin magnetic films are at the resolution limit of TEM imaging. “Distinguishing magnetic textures, like skyrmions, from structural defects is challenging. We developed custom imaging recipes and computational analysis techniques to address this,” Tan said.

Initial attempts to regulate skyrmions by altering the thickness of a single magnetic layer to manipulate IEC were unsuccessful due to the skyrmions' high sensitivity. This prompted the exploration of IEC with a second magnetic layer, a strategy not previously considered by the community. The team discovered that fine-tuning this layer provided much more precise control over skyrmion numbers.

"With two chiral layers coupled together by the second IEC, fluctuations in one chiral layer can be restored by the second layer," Chen explained. "This greatly improves the stability of skyrmions in chiral bilayers, which host the second IEC."

Controlling skyrmions without a magnetic field enables scalable, energy-efficient computing technologies. Meanwhile, extending IEC beyond traditional materials can create exotic 3D textures by coupling layers with different or complementary properties.

"Our work opens up the third dimension of magnetic films as a playground for materials exploration," said Soumyanarayanan, adding that this breakthrough enabled the creation of the world's first all-electrical skyrmionic magnetic tunnel junction—an advanced, high-efficiency memory device that reads and writes data using purely electrical signals.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).

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References

Chen, X., Tai, T., Tan, H.R., Tan, H.K., Lim, R., et al. Tailoring zero-field magnetic skyrmions in chiral multilayers by a duet of interlayer exchange couplings. Advanced Functional Materials 34 (1), 2304560 (2024). | article

About the Researchers

Anjan Soumyanarayanan is a Research Scientist at A*STAR’s Institute of Materials Research and Engineering (IMRE), and an Assistant Professor at the Department of Physics, National University of Singapore (NUS). He received his PhD in Physics in 2013 from the Massachusetts Institute of Technology (MIT), USA. He leads the Spin Technology for Electronic Devices (SpEED) team at IMRE, and his research interests include topological and quantum phenomena in low-dimensional materials and devices towards applications in next-generation computing technologies.
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Xiaoye Chen

Scientific Consultant, Spin Technology for Electronic Devices (SpEED) team

Institute of Materials Research and Engineering (IMRE)
Xiaoye Chen is a Scientific Consultant of the Spin Technology for Electronic Devices (SpEED) team at A*STAR’s Institute of Materials Research and Engineering (IMRE). He was formerly a scientist at IMRE, where he specialised in magnetic materials and microscopy image analysis. He obtained his PhD in experimental physics from the University of Cambridge in 2017.
Hui Ru Tan is a Lead Research Engineer at A*STAR’s Institute of Materials Research and Engineering (IMRE). She received her PhD in Physics in 2017 from the National University of Singapore. She specialises in transmission electron microscopy (TEM), with unique expertise in magnetic imaging via a variety of electron microscopy techniques.

This article was made for A*STAR Research by Wildtype Media Group