Skyrmions are a few nanometers in size, very stable, and easily manipulated with spin-polarized currents that consume little power
By Brian Santo,
You just mistyped “Skyrim” into Google and ended up here, didn’t
you? Pull up a chair anyway. Skyrmions might not be as much fun as being
Dragonborn, but they’re pretty close. It starts with their classification; skyrmions
are among a set of bizarre phenomena called quasi-particles.
Quasiparticles have little in common with each other beyond
having no physical existence, yet having particle-like characteristics. The
list also includes bogoliubons, dropletons, phasons, rotons and wrinklons.
A skyrmion is a
point-like region of reversed magnetization in a uniform magnet. Image source: Alan
Skyrmions do not exist outside of magnetic fields. A single
skyrmion is a point-like region of reversed magnetization, surrounded by a
whirling twist of spins, according
to Christopher H. Marrows, a physicist at the UK’s University of Leeds School
of Physics and Astronomy, writing in the journal Physics.
The phenomenon was posited in 1962 but not observed until 2009.
Impressively, skyrmions could end up being the basis for the
next step in computer memory. Chip manufacturers worry that progress in
semiconductor memory technology development could conceivably hit a wall in the
not-too-distant future as they approach what appear to be strict limits in
physics with silicon-based DRAM and flash memory. Anything that might be a
viable replacement is being aggressively investigated, and skyrmion memories
might be a viable replacement.
Skyrmions are only a few nanometers in size, very stable,
and easily manipulated with spin-polarized currents that consume little power,
which makes them potentially suitable for computer memory for nanoelectronics systems,
Skyrmions are not evident in many materials, however. A
group of researchers from China has done some of the pioneering work in this
area, including discovering a material that is skyrmion-rich at room
temperature: CoFeB/MgO (cobalt-iron-boron/magnesium oxide).
They have also devised a skyrmion-based racetrack memory
(RM). RM memories are experimental, but intriguing because they combine a set
of performance traits that suggest they could succeed today’s DRAM and flash
memory. IBM has reported
success building RMs using silicon and a CMOS process (standard for silicon
The Chinese researchers describe the additional work
necessary to make their skyrmion-based memory practical but believe it might
end up a better option than silicon-based RMs. “Skyrmion-based RM (Sky-RM) is
promising to achieve lower energy cost, higher device packing density, and more
robust data stability,” they said
in their paper.
The Chinese researchers are also exploring other potential
applications, one of which they say might not be possible without a
skyrmion-based device. In January, they described a skyrmion-based artificial
synapse device for neuromorphic systems. They caution that they have
managed only a rudimentary simulation, but they have devised a variation of an
RM in which skyrmions could be induced to behave in a manner that mimics the
way synapses work.