Collective ferromagnetism of artificial square spin ice

TL;DR

This study investigates how temperature, magnetic field, and inter-island interactions influence the magnetic behavior of artificial square spin ice arrays, revealing complex reversal mechanisms and potential for property tuning.

Contribution

It provides new insights into the effects of inter-island interactions and shape details on magnetization reversal in artificial spin ice, supported by experiments and micromagnetic simulations.

Findings

Deviations from the Stoner-Wohlfarth model at small lattice spacing.

Inter-island interactions induce complex magnetization reversal.

Shape details critically influence magnetic behavior.

Abstract

We have studied the temperature and magnetic field dependence of the total magnetic moment of large-area permalloy artificial square spin ice arrays. The temperature dependence and hysteresis behavior are consistent with the coherent magnetization reversal expected in the Stoner-Wohlfarth model, with clear deviations due to inter-island interactions at small lattice spacing. Through micromagnetic simulations, we explore this behavior and demonstrate that the deviations result from increasingly complex magnetization reversal at small lattice spacing, induced by inter-island interactions, and depending critically on details of the island shapes. These results establish new means to tune the physical properties of artificial spin ice structures and other interacting nanomagnet systems, such as patterned magnetic media.