Magneto-optical Kerr Effect Studies of Square Artificial Spin Ice

TL;DR

This study uses magneto-optical Kerr effect measurements to explore how anisotropic interactions and edge roughness influence the magnetic behavior of artificial square spin ice arrays, revealing the significant role of disorder.

Contribution

It demonstrates the impact of edge roughness-induced disorder on the collective magnetic response of artificial square spin ice, supported by experimental and micromagnetic simulation comparisons.

Findings

Anisotropic interactions cause non-monotonic coercive field dependence on angle.

Edge roughness affects the magnetization reversal process.

Disorder from roughness is crucial in collective magnetic behavior.

Abstract

We report a magneto-optical Kerr effect study of the collective magnetic response of artificial square spin ice, a lithographically-defined array of single-domain ferromagnetic islands. We find that the anisotropic inter-island interactions lead to a non-monotonic angular dependence of the array coercive field. Comparisons with micromagnetic simulations indicate that the two perpendicular sublattices exhibit distinct responses to island edge roughness, which clearly influence the magnetization reversal process. Furthermore, such comparisons demonstrate that disorder associated with roughness in the island edges plays a hitherto unrecognized but essential role in the collective behavior of these systems.