Two-axis cavity optomechanical torque characterization of magnetic microstructures

TL;DR

This paper introduces a two-axis cavity optomechanical technique for detailed magnetic characterization of microstructures, enabling separation of magnetic moment and susceptibility contributions with high sensitivity to edge domains and spin dynamics.

Contribution

The study presents a novel two-axis torque measurement method that distinguishes magnetic properties in microstructures, advancing magnetic characterization capabilities.

Findings

Effective separation of magnetic moment and susceptibility contributions.

High sensitivity to small edge domain effects.

Potential coupling to spin dynamics at mechanical resonance frequencies.

Abstract

Significant new functionality is reported for torsion mechanical tools aimed at full magnetic characterizations of both spin statics and dynamics in micro- and nanostructures. Specifically, two orthogonal torque directions are monitored and the results co-analyzed to separate magnetic moment and magnetic susceptibility contributions to torque, as is desired for characterization of anisotropic three-dimensional structures. The approach is demonstrated through application to shape and microstructural disorder-induced magnetic anisotropies in lithographically patterned permalloy, and will have utility for the determination of important magnetic thin-film and multilayer properties including interface anisotropy and exchange bias. The results reflect remarkable sensitivity of the out-of-plane magnetic torque to the nature of small edge domains perpendicular to the applied field direction, and also contain tantalizing indications of direct coupling to spin dynamics at the frequency of the mechanics.