Enhanced gyration-signal propagation speed in one-dimensional   vortex-antivortex lattices and its control by perpendicular bias field
  We report on a micromagnetic simulation study of coupled core gyrations in one-dimensional (1D) alternating vortex-antivortex (V-AV) lattices formed in connected soft-magnetic-disk arrays (round-shaped modulated nanostrips). In the V-AV lattices, we found very characteristic standing-wave modes of the coupled gyrations as well as efficiently ultrafast gyration-signal propagation between vortices through the neighboring antivortices, as originating from their combined strong exchange and dipole interactions. Collective core oscillations in the V-AV networks are characterized as unique two-branch magnonic bands that are affected by the polarization ordering between the neighboring vortex and antivortex and controllable by externally applied perpendicular fields each of different field strength and direction. The gyration-signal propagation speed is much faster than that for 1D disk arrays composed only of vortex states, and the propagation speed for the parallel polarization ordering is increased, remarkably, to more than 1 km/sec by application of perpendicular static fields. This work provides a fundamental understanding of the coupled dynamics of topological solitons as well as an additional mechanism for ultrafast gyration-signal propagation; moreover, it offers an efficient means of significant propagation-speed enhancement that is suitable for information carrier applications in continuous nanostrips. 
Sang-Koog Kim and Han-Byeol Jeong
cond-mat.mes-hall