Scientists at the US Department of Energy’s Ames lab have discovered the relaxation dynamics of a zero-field state in skyrmions, a rotating magnetic phenomenon that has potential applications in data storage and spintronic devices.
Skyrmions are nano-scale vortices or vortices of magnetic poles that form networks inside a magnetic material, a type of quasi-particle that can pass through the material, driven by electric current. These properties have captured the fascination of scientists, who believe the phenomenon could lead to the next big breakthrough in data storage, making digital technology even faster and smaller.
However, there are big challenges to overcome. Until recently, skyrmions were only a phenomenon observed at extremely low temperatures. In addition, external magnetic forces currently make them impractical for applications.
“To be truly useful in a device, these magnetic vortices must be able to exist without the ‘help’ of an external magnetic field,” said Lin Zhou, a scientist in the Materials Science and Engineering Division of the Ames Laboratory. .
With that in mind, she and other researchers in the Ames lab studied FeGe, an iron-germanium magnetic material that has demonstrated skyrmions in the highest temperature ranges to date in similarly structured crystals or B20.
Ames Lab scientists with external collaborators were able to establish an array of skyrmions in a sample through exposure to magnetic fields and supercooling with liquid nitrogen. With a high-resolution microscopy method called Lorentz Transmission Electron Microscopy (L-TEM), the team was able to observe the skyrmion array in a zero magnetic field, then observe the skyrmion decay as the temperature warmed. . This direct observation has provided essential new information on the behavior of skyrmions and their return to a “normal” magnetic state (what scientists call metastable).
“We stabilized these skyrmions without a magnetic field, and our microscopy techniques allowed us to really see how vortices change over time, temperature and magnetic field; we believe this provides a very solid basis for theorists to better understand this phenomenon, “Zhou said.
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