Remanence of Ni nanowire arrays: Influence of size and labyrinth magnetic structure

TL;DR

This study investigates how the size and magnetic structure of Ni nanowire arrays affect their remanence, using a phenomenological model and magnetic force microscopy to analyze magnetic states and interactions.

Contribution

The paper introduces a simple model linking remanence to magnetostatic interactions and explores the magnetic ordering in nanowire arrays through experimental imaging.

Findings

Remanence strongly depends on sample size due to dipolar interactions.

Magnetic force microscopy reveals labyrinth patterns from competing short-range orders.

Two magnetic states with similar energies explain observed magnetic structures.

Abstract

The influence of the macroscopic size of the Ni nanowire array system on their remanence state has been investigated. A simple magnetic phenomenological model has been developed to obtain the remanence as a function of the magnetostatic interactions in the array. We observe that, due to the long range of the dipolar interactions between the wires, the size of the sample strongly influence the remanence of the array. On the other hand, the magnetic state of nanowires has been studied by variable field magnetic force microscopy for different remanent states. The distribution of nanowires with the magnetization in up or down directions and the subsequent remanent magnetization has been deduced from the magnetic images. The existence of two short-range magnetic orderings with similar energies can explain the typical labyrinth pattern observed in magnetic force microscopy images of the nanowire arrays.