Unlocking the recipe for Designer Magnet Pa

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Traditional computing is increasingly being replaced by artificial intelligence (AI) techniques to achieve pattern recognition capabilities in many fields, including healthcare, manufacturing, and personal computing. The increasing complexity of the “neural networks” required for AI capabilities leads to an exponential increase in energy consumption. In view of ever tighter energy budgets, the need for data processing at the collection point, the so-called edge, is growing, especially for real-time applications.

Enter small but mighty skyrmions – tiny, tortuous arrays of electron spins that form in certain magnetic thin films. These energy-efficient information carriers are stable at room temperature and can be moved by electrical currents, potentially mimicking how signals are sent and received by biological nerve cells in the human brain.

At extremely small nanoscale sizes, skyrmions can be 100 times smaller than the magnetic regions used in conventional hard drives, making potential skyrmion-based devices very compact. This makes them promising candidates for use in future computing devices to realize low-power neural network applications.

“Magnetic skyrmions are uniquely positioned because they are of scientific interest, are stable in industry-compatible materials and environments, and have applications in cutting-edge computational problems,” said Dr. Xiaoye Chen from the Spin Technology for Electronic Devices (SpEED) team at A *Institute for Materials Research and Engineering (IMRE) of STAR.

“With superior properties such as nanoscale size, high stability and low-power operation, magnetic skyrmions can be a powerful solution for the development of innovative reconfigurable neural computing technologies,” added Dr. Mi-Young Im, a research associate at Lawrence Berkeley National Laboratory’s Center for X-ray optics (CXRO).

MEETING SKYRMIONS: WHAT MAKES THEM THE WAY THEY ARE?

In order to design skyrmions with the desired properties suitable for device-specific requirements, it is important to understand which material properties influence their structure and stability.

Researchers from IMRE and the Institute of High Performance Computing (IHPC) at A*STAR, the National University of Singapore (NUS) and CXRO at Lawrence Berkeley National Laboratory (LBNL) have collaborated to study factors affecting key physical properties of skyrmions in thin magnetism affect films, in a Study published in Advanced Science in January 2022.

TRANSFORMING THE SKYRMIONS’ PROPERTIES: ADJUSTING THE MAGIC PARAMETERS

The team used a thin-film magnetic platform that includes a sequential stack of atomically thin metal layers previously developed at A*STAR. This multi-layer platform uniquely allows the magnetic interactions that determine skyrmion properties to be directly controlled by varying the thickness of each layer.

The team studied the spin structures formed in these thin films using a range of specialized magnetic imaging methods, including electron microscopy and soft X-ray microscopy, as well as simulation techniques such as ab initio and micromagnetic calculations.

Interestingly, the team found that several key properties of magnetic skyrmions could be tuned by varying a single material parameter, 𝜅, which roughly represents the “ease” of generating spin structures within the material.

First, increasing the 𝜅value of zero causes a sharp change in the tortuous arrangement of spins forming the skyrmion, known as its “helicity”, which then becomes fixed for larger values ​​of 𝜅.

Next increase 𝜅 changes the elasticity or “compressibility” of skyrmions. For smaller ones 𝜅-Values ​​can shrink and expand skyrmions slightly, similar to soap bubbles. But for bigger ones 𝜅-values ​​they are very compact, like billiard balls.

Finally, increasing 𝜅 further changes how skyrmions are generated from elongated, meandering magnetic domains called “stripes”. For smaller ones 𝜅-Values, streaks shrink to individual skyrmions, while for larger ones 𝜅values, a stripe can split or “split” into multiple skyrmions.

Overall, the work provides a material-based framework for controlling skyrmion properties for future use in devices.

HEAT ON: FROM STRIPE TO SKYRMIONS

In a sequel Study published in Physical review applied in April 2022, the team used a combination of magnetometry, imaging and simulation techniques to study the temperature dependence of the stripe-to-skyrmion transition.

Their work found that as the temperature increases, each streak splits or splits into a greater number of skyrmions, resulting in an increase in the density of skyrmions. This knowledge of the influence of temperature on skyrmions offers opportunities for future technological developments where controlled temperature cycling can be used for efficient skyrmion generation in future unconventional computing applications.

DEAL CLOSED: CUSTOM SKYRMIONS, OPTIMIZED FOR PERFORMANCE

Because both studies provide a comprehensive framework for controlling skyrmion properties, creating custom skyrmions with properties tailored to different applications is closer to reality. For example, electrical devices can use either skyrmion size or skyrmion count to perform logical operations that could use either low 𝜅 or high 𝜅 materials. In due course, this could enable the development of skyrmionic devices for next-generation computers.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of the press releases published on EurekAlert! by contributing institutions or for the use of information about the EurekAlert system.

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