For the first time, researchers have taken a microscopic look at this process. The international team has now published their results on July 11, 2019 inCommunications Physics, a Nature journal.
In certain conductive materials, such as Manganese Silicon (MnSi), the quasiparticles can accumulate into a magnetic skyrmion with a vortex-like shape and motion. The skyrmion creates a lattice of connection points within the MnSi crystal.
"Magnetic skyrmions have attracted interest due to the potential for spintronics applications", stated Taku Sato, study author and professor at the Institute of Multidisciplinary Research for Advanced Materials at Tohoku University.
Spintronics refer to theoretical electronics that rely not only on the charge state of a current, but also on the characteristics of electrons to transfer and store quantum information.
"The first step to realize such spintronic applications of skyrmions may be electric current control of skyrmion flow", Taku Sato stated. "Once created, the skyrmion can almost never be annihilated. It also strongly couples to electric current flow, meaning it takes very little current to move the system."
To understand how electric current affects the magnetic skyrmion changes under an electrical current, the researchers used a method called small-angle neutron scattering. They powered a neutron beam through a MnSi crystal, causing the skyrmion particles to react - the neutrons literally scatter against and around the components of the skyrmion system. How they scatter tells the researchers about the system.
In this case, the researchers saw that the lattice structure of the skyrmion was deformed, causing the vortex motion of the skyrmion to change. They also saw that the edges of the skyrmion were significantly disturbed, almost as if it were pushing against itself. Taku Sato attributes this to what he called "pinned edges". The skyrmion might push against its outermost limits, causing friction.
"Such a friction effect has not been reported to date as far as we are aware of", Taku Sato stated. "It's fundamental key information for the realistic spintronics device design utilizing magnetic sykrmions."
Taku Sato and his team plan to further investigate the dynamics of magnetic skyrmions with the eventual goal of developing spintronic devices.
The paper titled " Deformation of the moving magnetic skyrmion lattice in MnSi under electric current flow " is authored by D. Okuyama, M. Bleuel, J.S. White, Q. Ye, J. Krzywon, G. Nagy, Z.Q. Im, I. Zivkovic, M. Bartkowiak, H.M. Rønnow, S. Hoshino, J. Iwasaki, N. Nagaosa, A. Kikkawa, Y. Taguchi, Y. Tokura, D. Higashi, J.D. Reim, Y. Nambu, and T.J. Sato. It is published inCommunications Physics- DOI: 10.1038/s42005-019-0175-z.