How to save data in vortex structures

Back in 2009, Professor Christian Pfleiderer and his physics team discovered an entirely new magnetic structure in a silicon manganese crystal – a grid of magnetic eddies.

Pfleiderer, of the Technische Universität München (TUM), subsequently teamed up with Professor Achim Rosch from the University of Cologne to study the properties of these eddies. Dubbed skyrmions, the eddies were named after the British physicist Tony Skyrme, who predicted their existence some 50 years ago. 

Pfleiderer and Rosch were expecting results in the field of spintronics: nano-electric components that utilize not only the electric charge of electrons for processing information, but also their magnetic momentum, known as spin.

Indeed, current research in the field tends to focus on how magnetic information can be written directly to materials via electric current.

However, the extremely strong electric currents required produces side effects, which are practically untamable, even in nano-structures. Fortunately, skyrmions can be moved with 100,000 times less current. 

Although magnetic eddies were initially discovered in silicon manganese, it was clear that the medium wouldn’t remain the only material capable of generating skyrmions. Since then, Japanese researchers have proven that individual eddies can be generated, while a group of physicists from the Research Center Jülich, as well as the Universities of Hamburg and Kiel, provided evidence that magnetic eddies can be generated on surfaces. 

The latter group even managed to build a data bit out of only 15 atoms. By way of comparison, a magnetic bit on a common hard drive requires about one million atoms.

Nevertheless, despite such advances, writing, updating and reading information remained a problem. As such, Pfleiderer’s team resorted to neutron radiation from the neighboring research reactor FRM II at the TU Muenchen to study the materials.

“We can just take the crystals generated in our laboratory at the physics department, walk over there and use the neutrons to measure the magnetic structure, its dynamics and many other properties,” he explained. 

Using neutron radiation, the scientists were able to prove that even the tiniest of currents are sufficient to move the magnetic eddies. This allowed the physicists to develop a method by which skyrmions can be moved and measured in a purely electronic manner. 

“When the electric eddies move in a material, they generate an electric field,” said Pfleiderer. “And that is something we can measure directly with electronic equipment available in our laboratory.”

At present, a current is used in the read/write head of a hard drive to generate a magnetic field in order to magnetize a spot on the hard drive and thus write a data bit. In contrast, Skyrmions can be moved directly – and with very small currents.

“This should make saving and processing data much more compact and energy-efficient,” he added.

It should be noted that precise measuring of skyrmions is still heavily contingent upon very low temperatures – and will require a significant amount of research before the eddies can be exploited in any real world scenario.