Researchers observe unique chiral magnetic phenomenon

June 29, 2018, Forschungszentrum Juelich
Encoding digital data as a sequence of magnetic bobbers (foreground) and skyrmions (further back). Credit: Forschungszentrum Jülich/N. Kiselev

Tiny magnetic vortex structures, so-called skyrmions, have been researched intensively for some time for future energy-efficient space-saving data storage devices. Scientists at Forschungszentrum Jülich have now discovered another class of particle-like magnetic object that could take the development of data storage devices a significant step forward. The newly discovered magnetic particles make it possible to encode digital data directly with two different types of magnetic objects, namely with skyrmions and magnetic bobbers—if skyrmions are used to encode the number one, then the new structures could be used to encode the number zero.

These objects, which are referred to as "chiral magnetic bobbers," are three-dimensional that appear near the surfaces of certain alloys.

"For a long time, the unique object for research in the field of chiral magnets was the magnetic skyrmion. We now provide a new for investigation by researchers—a chiral bobber—which is characterized by a number of unique properties," says Dr. Nikolai Kiselev from Jülich's Peter Grünberg Institute (PGI-1). Three years ago, together with the institute's Director Prof. Stefan Blügel and other collaborators, they predicted the existence of this new class of magnetic structures theoretically. Now, researchers from the Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (Director Prof. Rafal E. Dunin-Borkowski and his colleagues) have demonstrated the existence of chiral bobbers in a real material experimentally.

The stability of magnetic structures such as skyrmions is related to a property of the material known as chirality. Just as a right hand cannot be converted into a left hand for reasons of symmetry, right-handed and left-handed magnetic structures cannot be converted into one another. Furthermore, both skyrmions and the newly-discovered chiral bobbers are very small, with diameters of typically only a few tens of nanometers. Therefore, they can in principle be used to pack data very densely on a memory chip. However, their small size makes their observation highly challenging. "The visualization of magnetic texture on such a small scale requires special state-of-the-art techniques that are accessible in only a few laboratories worldwide," explains Rafal Dunin-Borkowski.

The concept of racetrack memory: magnetic objects move from writing to reading elements. Credit: Forschungszentrum Jülich

There is another important reason why magnetic solitons (another name for particle-like objects in nonlinear physics) such as skyrmions and chiral bobbers are so promising for applications. In contrast to data bits in hard disk drives, skyrmions are movable objects. Their motion along a guiding track in a chip can be induced by a very weak pulse of electrical current. This property provides new opportunities for the development of a completely new concept of magnetic solid-state memory—the so-called racetrack memory. "The mobility of skyrmions allows data to move from write to read elements without the need for any movable mechanical parts such as read and write heads and spining hard disk itself," explains Nikolai Kiselev. This capability saves energy because components that move generally require more energy, occupy more space and tend to be sensitive to mechanical vibrations and shocks. A new solid state magnetic memory would be free of such disadvantages.

"Until now, it was assumed that digital data should somehow be represented as a sequence of skyrmions and empty spaces," says Stefan Blügel. The distance between successive skyrmions then encodes binary information. However, it must then be controlled or quantized, so that no information is lost through spontaneous drift of the skyrmions. Instead, the newly discovered three-dimensional magnetic particles offer opportunities to encode directly as a sequence of skyrmions and magnetic bobbers, which can each flow freely without needing to maintain precise distances between successive data bit carriers.

Further research is required to develop practical applications. In the iron-germanium alloy studied by Nikolai Kiselev and his colleagues, the structures are only stable up to 200 Kelvin, which corresponds to -73.5 degrees Celsius. However, based on theoretical considerations, it is predicted that magnetic bobbers may also occur in other chiral magnets and, like some recently discovered species of skyrmions, may also exist at room temperature.

Explore further: Bit data goes anti-skyrmions

More information: Fengshan Zheng et al, Experimental observation of chiral magnetic bobbers in B20-type FeGe, Nature Nanotechnology (2018). DOI: 10.1038/s41565-018-0093-3

Related Stories

Bit data goes anti-skyrmions

September 1, 2017

Today's world, rapidly changing because of "big data", is encapsulated in trillions of tiny magnetic objects - magnetic bits - each of which stores one bit of data in magnetic disk drives. A group of scientists from the Max ...

Unlocking the potential of magnetic skyrmions

November 2, 2017

Magnetic skyrmions offer the promise of next-generation memory and computing technologies, such as cache memory devices and cloud computing. Now A*STAR researchers have developed an innovative technique for making tunable ...

Frustrated magnets point towards new memory

September 23, 2015

Theoretical physicists from the University of Groningen, supported by the FOM Foundation, have discovered that so-called 'frustrated magnets' can produce skyrmions, tiny magnetic vortices that may be used in memory storage. ...

Controlling skyrmions with lasers

March 2, 2018

EPFL scientists have produced controllable stable skyrmions using laser pulses, taking a step towards significantly more energy-efficient memory devices. The work is published in Physical Review Letters.

Recommended for you

Targeting headaches and tumors with nano-submarines

July 20, 2018

Scientists at the Mainz University Medical Center and the Max Planck Institute for Polymer Research (MPI-P) have developed a new method to enable miniature drug-filled nanocarriers to dock on to immune cells, which in turn ...

Splitting water: Nanoscale imaging yields key insights

July 18, 2018

In the quest to realize artificial photosynthesis to convert sunlight, water, and carbon dioxide into fuel—just as plants do—researchers need to not only identify materials to efficiently perform photoelectrochemical ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.