Magnetic skyrmions.
Credit: Image courtesy of RIKEN
In research published in Nature Communications,
researchers from the RIKEN Center for Emergent Matter Science in Japan,
along with collaborators in Europe and Japan, have identified a class
of materials that displays clear evidence for stable skyrmions at room
temperature and above, paving the way for the development of useful
spintronics devices.
Magnetic skyrmions are tiny, nanometer-sized magnetic-spin vortices
that emerge on the surface of magnetic materials. Because they are so
small, they could potentially be used as extremely dense memory devices,
with the presence or absence of skyrmions, or the direction of spin,
being used to denote bits in computer calculations. Achieving this could
lead to the advent of a new class of low-power-consumption devices
dubbed "spintronics," as well as ultra-low consumption, high-density
magnetic memory.
However, skyrmions are not always easy to use. Though they occur
ubiquitously in magnets, in a diverse range of circumstances, they are
not always easy to control. The ultimate dream of researchers has been
to create stable skyrmions -- which do not decay -- in a set chirality,
so that their chirality can be manipulated to represents data for
storage devices
Skyrmions emerging from a process called the Dzyaloshinskii-Moriya
interaction have been considered to be particularly promising, as they
are small (under 150 nanometers) and have a fixed direction of spin, so
that they could host a large number of stable skyrmions which could be
manipulated by electrical currents, and hence could be used to create
high-density storage. Such stable skyrmions have been found in certain
crystal structures, but in the materials studied so far, such as
Cu2OSeO3, the skyrmions emerge most strongly in low temperatures,
requiring low-temperature manipulation.
For the present study, the scientists decided to look at a type of
magnetic material made up of cobalt, zinc, and manganese, whose
structure seemed likely to host stable skyrmions. Using a variety of
techniques, they were able to show indeed that when a magnetic field was
applied, the material showed the clear presence of skyrmion crystals in
both a bulk shape and when shaped into a thin plate. These skyrmions
were both stable and chiral -- meaning that they spun in a set direction
-- so that they could be manipulated to encode information depending on
the chirality.
According to Yusuke Tokunaga of CEMS, who performed the work, "We are
quite excited about these results, as they may answer the long-held
expectation that we can find skyrmion hosting systems in a variety of
new materials. In addition, the fact that we have shown that skyrmions
can be stabilized at room temperature and above opens the road to
looking for ways to integrate skyrmions into spintronics devices without
complicated cooling systems.
The research was done by CEMS scientists in collaboration with
scientists from the Paul Scherrer Institut and Ecole Polytechnique
Federale de Lausanne in Switzerland and the University of Tokyo in
Japan.
Story Source:
The above post is reprinted from
materials provided by
RIKEN.
Note: Materials may be edited for content and length.
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