Nano-Torsional Resonator Torque Magnetometry

TL;DR

This paper demonstrates a highly sensitive nano-torsional resonator system for measuring magnetic torque in nanomagnetic elements using optical interferometry, enabling detailed magnetic behavior analysis at the nanoscale.

Contribution

It introduces a novel fabrication and measurement technique combining focused-ion-beam milling and optical interferometry for nanoscale magnetic torque detection.

Findings

Achieved sensitivity of approximately 10^8 Bohr magnetons

Successfully measured magnetic behavior of single nanomagnetic elements

Demonstrated resonance-based detection of magnetization vectors

Abstract

Magnetic torque is used to actuate nano-torsional resonators, which are fabricated by focused-ion-beam milling of permalloy coated silicon nitride membranes. Optical interferometry is used to measure the mechanical response of two torsion modes at resonance, which is proportional to the magnetization vector of the nanomagnetic volume. By varying the bias magnetic field, the magnetic behavior can be measured with excellent sensitivity ($\approx 10^8 \mu_B$) for single magnetic elements.