Current-controlled propagation of spin waves in antiparallel, coupled domains

Spin waves may constitute key components of low-power spintronic devices. Antiferromagnetic-type spin waves are innately high-speed, stable and dual-polarized. So far, it has remained challenging to excite and manipulate antiferromagnetic-type propagating spin waves. Here, we investigate spin waves in periodic 100-nm-wide stripe domains with alternating upward and downward magnetization in La_0.67Sr_0.33MnO₃ thin films. In addition to ordinary low-frequency modes, a high-frequency mode around 10 GHz is observed and propagates along the stripe domains with a spin-wave dispersion different from the low-frequency mode. Based on a theoretical model that considers two oppositely oriented coupled domains, this high-frequency mode is accounted for as an effective antiferromagnetic spin-wave mode. The spin waves exhibit group velocities of 2.6 km s^-1 and propagate even at zero magnetic bias field. An electric current pulse with a density of only 10⁵ A cm^-2 can controllably modify the orientation of the stripe domains, which opens up perspectives for reconfigurable magnonic devices.