Wave dynamics in a macroscopic square artificial spin ice

Abstract

A macroscopic square artificial spin ice, or macro-ASI, is a collection of bar magnets placed in a square lattice arrangement. Each magnet is supported by hinges that allow their mechanical rotation. Previous investigations in these structures have shown ground-state configurations and driven dynamics similar to those of their nanosized counterparts. Here, we numerically investigate the impact of a defect, a Dirac string, on the driven dynamics. We find that waves quickly lose coherence by scattering between modes in this system. In addition, we observe a distinct mode associated with the isolated oscillation of the Dirac string. As expected from spatial localization, this resonant mode is under the band of propagating waves in the macro-ASI. The results are analogous to the development of low-frequency edge modes in nanoscopic spin ices in the presence of defects. Our results provide valuable insight into the physics of mechano-magnetic systems, demonstrating the existence of wave scattering and spatial confinement phenomena in macro-ASIs.