Fast current-driven domain walls and small skyrmions in a compensated ferrimagnet.

Spintronics is a research field that aims to understand and control spins on the nanoscale and should enable next-generation data storage and manipulation. One technological and scientific key challenge is to stabilize small spin textures and to move them efficiently with high velocities. For a long time, research focused on ferromagnetic materials, but ferromagnets show fundamental limits for speed and size. Here, we circumvent these limits using compensated ferrimagnets. Using ferrimagnetic Pt/Gd ₄₄ Co ₅₆ /TaO _x films with a sizeable Dzyaloshinskii-Moriya interaction, we realize a current-driven domain wall motion with a speed of 1.3 km s ^-1 near the angular momentum compensation temperature (T _A ) and room-temperature-stable skyrmions with minimum diameters close to 10 nm near the magnetic compensation temperature (T _M ). Both the size and dynamics of the ferrimagnet are in excellent agreement with a simplified effective ferromagnet theory. Our work shows that high-speed, high-density spintronics devices based on current-driven spin textures can be realized using materials in which T _A and T _M are close together.