Characterization of switching field distributions in Ising-like magnetic arrays

TL;DR

This study uses spatially resolved Kerr imaging to analyze the switching field distributions in magnetic island arrays, distinguishing the effects of disorder and interactions on magnetization dynamics.

Contribution

It introduces a method to separate disorder and interaction effects in switching fields of magnetic arrays using individual island tracking.

Findings

Disorder mainly arises from island properties, not interactions.

A simple model explains the switching field distribution width.

Interactions contribute a field proportional to maximum array polarization.

Abstract

The switching field distribution within arrays of single-domain ferromagnetic islands incorpo- rates both island-island interactions and quenched disorder in island geometry. Separating these two contributions is important for disentangling the effects of disorder and interactions in the magnetization dynamics of island arrays. Using sub-micron, spatially resolved Kerr imaging in an external magnetic field for islands with perpendicular magnetic anisotropy, we map out the evolution of island arrays during hysteresis loops. Resolving and tracking individual islands across four different lattice types and a range of inter-island spacings, we extract the individual switching fields of every island and thereby determine the relative contributions of interactions and quenched disorder in the arrays. The width of the switching field distribution is well explained by a simple model comprising the sum of an array-independent contribution (interpreted as disorder-induced), and a term proportional to the maximum field the fully polarized array could exert on a single island. We conclude that disorder in these arrays is primarily a single-island property.