Wave dynamics in a macroscopic square artificial spin ice

TL;DR

This study explores wave behavior and defect effects in a macroscopic square artificial spin ice, revealing wave scattering, mode localization, and the impact of defects on driven magnetic dynamics.

Contribution

It introduces a numerical analysis of defect-induced phenomena and wave dynamics in macro-ASI, highlighting the effects of Dirac strings on coherence and mode localization.

Findings

Waves lose coherence due to scattering between modes.

A localized resonant mode is associated with the Dirac string.

Defects induce phenomena similar to edge modes in nanoscale spin ices.

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.