Dynamic cantilever magnetometry of individual CoFeB nanotubes

TL;DR

This study uses dynamic cantilever magnetometry to analyze individual CoFeB nanotubes, developing models and revealing magnetic configurations, including flux-closure states, with high sensitivity that surpasses ensemble measurements.

Contribution

The paper introduces a combined analytical and numerical framework for DCM analysis of magnetic nanostructures and demonstrates its effectiveness on individual CoFeB nanotubes.

Findings

Detection of uniform magnetization at high fields with M_s = 1.3 T

Observation of flux-closure configurations at low fields

High sensitivity of DCM to single nanotubes enables detection of configurations obscured in ensemble measurements

Abstract

We investigate single CoFeB nanotubes with hexagonal cross-section using dynamic cantilever magnetometry (DCM). We develop both an analytical model based on the Stoner-Wohlfarth approximation and a broadly applicable numerical framework for analyzing DCM measurements of magnetic nanostructures. Magnetometry data show the presence of a uniformly magnetized configuration at high external fields with $\mu_0 M_s =1.3 \pm 0.1$ T and non-uniform configurations at low fields. In this low-field regime, comparison between numerical simulations and DCM measurements supports the existence of flux-closure configurations. Crucially, evidence of such configurations is only apparent because of the sensitivity of DCM to single nanotubes, whereas conventional measurements of ensembles are often obscured by sample-to-sample inhomogeneities in size, shape, and orientation