Skyrmions are not fundamental pieces of matter; they are effects named after the physicist who proposed them. Until just recently, magnetic skyrmions had only been seen at very low temperatures and under powerful magnetic fields.
The magnetic force in each individual atom in a magnet - what physicists call their ‘magnetic moments’ - all line up the same way, like tiny compasses all pointing in the same direction. But under extreme conditions, certain magnetic materials can develop spots where the moments curve and twist, forming a ring-like configuration. These unusual objects possess an elasticity that protects them from outside influence, meaning the data they store would not be corrupted easily, even by stray magnetic fields or physical defects within the material. As a result, magnetic skyrmions present a promising basis for information memory systems and other nanoelectronic devices.
A hurdle in using traditional skyrmions was the extreme lab conditions needed to form them. While NIST's Dustin Gilbert was a graduate student at the University of California, Davis, he designed an approach to make the quantum objects remain stable at room temperature with no magnetic field.
Creating skyrmions involves placing arrays of tiny magnetised cobalt disks on top of a thin film made of cobalt and palladium; the NIST Centre for Neutron Research (NCNR) had just developed a state-of-art polarised neutron reflectometer that was well suited to study Gilbert’s lab results. Working with NCNR scientists, the team used neutrons to see through the disk to spot the skyrmions underneath. The team also captured images of the whirling configurations in the disk array at NIST's Centre for Nanoscale Science and Technology and Lawrence Berkeley Laboratory.
"The idea that has been discussed is that you could push these stable magnetic bundles in single file down a line and read their data. The advantage here is that you'd need way less power to push them around than any other method proposed for spintronics," says Gilbert. "What we need to do next is figure out how to make them move around. But for now, we can start exploring how we might use skyrmions in technology."
