Room-Temperature Current-Induced Generation and Motion of sub-100 nm Skyrmions

Magnetic
skyrmions are nanoscale windings of the spin configuration
that hold great promise for technology due to their topology-related
properties and extremely reduced sizes. After the recent observation
at room temperature of sub-100 nm skyrmions stabilized by interfacial
chiral interaction in magnetic multilayers, several pending questions
remain to be solved, notably about the means to nucleate individual
compact skyrmions or the exact nature of their motion. In this study,
a method leading to the formation of magnetic skyrmions in a micrometer-sized
track using homogeneous current injection is evidenced. Spin-transfer-induced
motion of these small electrical-current-generated skyrmions is then
demonstrated and the role of the out-of-plane magnetic field in the
stabilization of the moving skyrmions is also analyzed. The results
of these experimental observations of spin torque induced motion are
compared to micromagnetic simulations reproducing a granular type,
nonuniform magnetic multilayer in order to address the particularly
important role of the magnetic inhomogeneities on the current-induced
motion of sub-100 nm skyrmions for which the material grains size
is comparable to the skyrmion diameter.