Ultra-thin film could harness skyrmion quasiparticles for data storage

Scientists based at the National University of Singapore have developed a new ultra-thin film which could utilise the properties of skyrmions – particles comprised of tiny magnetic whirls – as next-generation information carriers. This is a significant step towards the development of more efficient data storage devices.

Magnetic skyrmions can only jump into existence within a magnetic field. They are points of reversed magnetisation, surrounded by a cloud of swirling magnetic spins.

These particles have been observed within layered systems, in which a heavy metal is placed beneath a ferromagnetic material (a permanent magnet). Within these systems, the materials interact, giving rise to a breaking of symmetry and the Dsyzaloshinskii-Moriya interaction (DMI), which stabilises skyrmions.

Without a magnetic field present, however, skyrmions become unstable. The team of researchers, led by Dr Yang Hyunsoo – an associate professor at the university’s department of electrical and computer engineering – set about working on how to stabilise these particles.

They found that they could maintain the DMI within a new material; a multilayer film composed of cobalt and palladium.

Collaborating with researchers from Brookhaven National Laboratory, Stoney Brook University and Lousiana State University, they observed the magnetic structure of the films. They used Lorentz transmission electron microscopy (L-TEM) – a technique never used for such an observation – and found that the new material stabilised the particles.

They could even observe the skyrmions in the absence of an external magnetic field. According to associate professor Yang Hyunsoo, who led the study, without the need to apply this field, the design and implementation of skyrmion-based devices is “significantly simplified”.

The researchers published their observations within this new material in Nature Communications.

“It has long been assumed that there is no DMI in a symmetric structure like the one present in our work, hence, there will be no skyrmion,” said Dr Shawn Pollard, a research fellow at the National University of Singapore, involved with the research.

“It is really unexpected for us to find both large DMI and skyrmions in the multilayer film we engineered. What’s more, these nanoscale skyrmions persisted even after the removal of an external biasing magnetic field, which are the first of their kind.”

Skyrmions have been discussed as a good candidate for data storage solutions due to being small, energy efficient and existing at room temperature. The presence or absence of a skyrmion would indicate the bit states 0 and 1. These states would be more energetically stable than is currently possible.

Skyrmion-based devices could offer a faster, more energy-efficient alternative to current data storage devices.

“The experiment […] opens up a completely new material in which skyrmions can be created,” said Associate Professor Yang Hyunsoo, who led the research.

“The small size of the skyrmions, combined with the incredible stability generated here, could be potentially useful for the design of next generation spintronic devices that are energy efficient and can outperform current memory technologies.”

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