Progress and challenges in magnetic skyrmionics

Abstract

Magnetic skyrmions are two-dimensional localized topological spin-structures characterized by the skyrmion number that measures the number of times of spins wrapping the Bloch sphere. Skyrmions behave like particles under an external stimulus and are promising information carriers. Skyrmions can exist as an isolated object as well as skyrmion condensates in crystal structures, helical/conical states, mazes or irregular stripy states with emergent electromagnetic fields. Thus, skyrmions provide a nice platform for studying fundamental physics, other than its applications in spintronics. In this perspective, we briefly review some recent progress in the field and present an outlook of the fundamental challenges in device applications.

Tuning nano-skyrmions and nano-skyrmioniums in Janus magnets

“…The efficient controlling topological charge is one of the most important fundamental problems in realizing skyrmion spin devices. 6,9 It is found that Q > 0 for B ≤ 0, whereas Q < 0 for B > 0 in Janus magnets in the right panel of Fig. 3, Fig.…”

“…[3][4][5] Furthermore, adjustments in the size and the topological charge are critical for constructing skyrmion-based spintronic devices. 6 Technically, adjustable skyrmions with a diameter of sub-10 nm are one of the requirements for ultradense and high speed skyrmionic nano-devices. However, the sizes of skyrmions in most magnetic materials are much larger than 10 nm.…”

In-plane spin excitation of skyrmion bags

“…Magnetic skyrmions, as topologically protected spin structures characterized by topological charges, have been widely studied in recent years. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Skyrmions have the characteristics of small size, topological protection, and low drive current density, which are conducive to the technical applications in high-density data storage equipment and low-energyconsumption spintronic devices. [18][19][20][21][22] In particular, the theoretical application of skyrmions has been extended to antiferromagnetic skyrmions, including racetrack memories, logic devices, spin nano-oscillators, and other promising spintronic devices derived from no spin Hall effect, zero stray field, and ultra-fast magnetization dynamics.…”

Thermal Stability of Skyrmion Tubes in Nanostructured Cuboids

“…Magnetic skyrmions are localized topological spin swirls that are potentially applicable in developing spintronic devices, due to their intriguing electromagnetic properties. − To achieve high-density skyrmion-based spintronic devices, it is necessary to investigate the geometrical confinement effect of nanostructures related to these devices. ,,, Previous studies have demonstrated the stabilization of skyrmions in nanodisks, , nanostripes, triangles, and tetrahedrons . Skyrmions exhibit remarkable stability and emergent topological magnetism in confined low-dimensional geometries. − …”

“…1−12 To achieve high-density skyrmion-based spintronic devices, it is necessary to investigate the geometrical confinement effect of nanostructures related to these devices. 3,6,12,13 Previous studies have demonstrated the stabilization of skyrmions in nanodisks, 14,15 nanostripes, 16 triangles, 17 and tetrahedrons. 18 Skyrmions exhibit remarkable stability and emergent topological magnetism in confined low-dimensional geometries.…”