Electric manipulation of skyrmions in metals and insulators

In this presentation, two recent examples of electrically manipulating skyrmions is discussed for magnetic multilayer systems, where the skyrmions can be stabilized at room-temperature. The first example is related to skyrmion generation in a metallic multilayer system. Magnetostatically stabilized skyrmion structures, magnetic bubbles, can form in magnetic thin films with perpendicular magnetic anisotropy. By adding an additional layer with strong spin-orbit coupling to the ferromagnet, it is possible to generate an interfacial chiral Dzyaloshinskii Moriya interaction, which stabilizes chiral magnetic domain walls around the bubble, resulting in a skyrmion spin structure. These skyrmion bubbles can then be electrically manipulated utilizing spin Hall effects. This is demonstrated for a Ta/CoFeB/TaO_x trilayer, where skyrmions can be generated via diverging electric charge currents in a process that is similar to droplet formation in surface-tension-driven fluid flow. This provides a practical approach for skyrmion formation on demand. Experimentally we determined the electric current vs . magnetic field phase diagram for the skyrmion formation and we demonstrated the manipulation of the dynamically created skyrmions. The resultant motion of the skyrmion bubbles is characterized by stochastic depinning due to random pinning sites.