Current-induced skyrmion generation and dynamics in symmetric bilayers

Magnetic skyrmions are textures behaving as quasiparticles which are topologically different from other states. Their discovery in systems with broken inversion symmetry sparked the search for materials containing such magnetic phase at room temperature. Their topological properties combined with the chirality-related spin-orbit torques make them interesting objects to control the magnetization at nanoscale. Here we show that a pair of coupled skyrmions with the same topological charge and opposite chiralities can be stabilized in a symmetric magnetic bilayer system by combining Dzyaloshinskii-Moriya interaction (DMI) and dipolar coupling effects. This effect opens a new path for skyrmion stabilization with much lower DMI. We then demonstrate in a single device with two different electrodes that such skyrmions can be efficiently and independently written and shifted by electric current at large velocities. The skyrmionic nature of the observed quasiparticles is further confirmed by using the gyrotropic force as a topological filter. These results set the ground for emerging spintronic technologies where issues concerning skyrmion stability, nucleation, and propagation are paramount.