New Opportunities for Spintronics: Magnetic Skyrmions

自旋电子的新机遇：磁性斯格明子

Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA

Prof. Axel Hoffmann is senior group leader of Magnetic Films Group at Argonne National Laboratory, Materials Science Division. Prof. Hoffmann has wide interesting in nanomagnetism, magnetic materials and spintronics. In addition, Prof. Hoffmann also services in many professional societies, such as Associate Editor of Journal of Applied Physics, American Institute of Physics, Member of IEEE Magnetic Society Advisory Committee, and American Physical Society.

Abstract: The field of spintronics, or magnetic electronics, is maturing and giving rise to new subfields. An important ingredient to the vitality of magnetism research in general is the large complexity due to competitions between interactions crossing many lengthscales and the interplay of magnetic degrees of freedom with charge (electric currents), phonon (heat), and photons (light). One perfect example, of the surprising new concepts being generated in magnetism research is the recent discovery of magnetic skyrmions. Magnetic skyrmions are topologically distinct spin textures that are stabilized by the interplay between applied magnetic fields, magnetic anisotropies, as well as symmetric and antisymmetric exchange interactions. Due to their topology magnetic skyrmions can be stable with quasi-particle like behavior, where they can be manipulated with very low electric currents. This makes them interesting for extreme low-power information technologies, where it is envisioned that data will be encoded in topological charges, instead of electronic charges as in conventional semiconducting devices. Towards the realization of this goal we demonstrated magnetic skyrmions in magnetic heterostructures stable at room temperature, which can be manipulated using spin Hall effects. Furthermore, using inhomogeneous electric charge currents allows the generation of skyrmions in a process that is remarkably similar to the droplet formation in surface-tension driven fluid flows. However, detailed micromagnetic simulations show that depending on the electric current magnitude there are at least two regimes with different skyrmion formation mechanisms. Lastly, we demonstrated that the topological charge gives rise to a transverse motion on the skyrmions, i.e., the skyrmion Hall effect, which is in analogy to the ordinary Hall effect originating from the motion of electrically charged particles in the presence of a magnetic field.

时间：2016 年 5 月24 日下午 4:00

地点：四川大学物理馆 323 阶梯教室