Phys. Rev. Lett. 114, 087203 (2015)

The controlled motion of magnetic domain walls in nanostructures is envisaged to be a promising tool for the development of spintronic devices for logic operations or information storage. Various driving mechanisms can generate the torques responsible for domain wall motion, from magnetic fields to spin currents. Spin waves — collective excitations of the electron spins in a crystal — carry spin currents and, when they traverse a domain wall, they displace it by transferring angular momentum to the local magnetic moments. Now, Hans Fangohr and colleagues at the University of Southampton show that in materials with certain magnetic properties spin waves can also exchange linear momentum with the domain walls, resulting in a 10-fold increase in domain wall velocity.

The key ingredients are the Dzyaloshinskii–Moriya interaction (DMI) and an easy-plane magnetic anisotropy. The researchers studied the domain wall dynamics in a nanowire by micromagnetic simulations and analytical models, using material parameters typical of FeGe, a material with bulk DMI. They show that velocities of a few metres per second can be achieved depending on the spin wave frequency, with a peak velocity at 24 GHz.