Simultaneous three-axis torque measurements of micromagnetism

TL;DR

This paper introduces a novel method for measuring all three components of magnetic torque simultaneously on micro- and nano-scale materials using a modified silicon resonator, enhancing magnetic characterization capabilities.

Contribution

A new technique for full three-axis magnetic torque measurement on micro- and nano-scale materials using a modified resonant sensor is demonstrated and validated.

Findings

Successful measurement of all three torque components

Enhanced understanding of magnetic hysteresis and anisotropy

Application to exchange bias studies

Abstract

Measurements of magnetic torque are most commonly preformed about a single axis or component of torque. Such measurements are very useful for hysteresis measurements of thin film structures in particular, where high shape anisotropy yields a near-proportionality of in-plane magnetic moment and the magnetic torque along the perpendicular in-plane axis. A technique to measure the full magnetic torque vector (three orthogonal torque components) on micro- and nano-scale magnetic materials is introduced. The method is demonstrated using a modified, single-paddle silicon-on-insulator resonant torque sensor. The mechanical compliances to all three orthogonal torque components are maximized by clamping the sensor at a single point. Mechanically-resonant AC torques are driven by an RF field containing a frequency component for each fundamental torsional mode of the device, and the resulting displacements read out through optical position-sensitive detection. The measurements are compared with micromagnetic simulations of the mechanical torque to augment the interpretation of the signals. As an application example, simultaneous observations of hysteresis in the net magnetization along with the field-dependent in-plane anisotropy is highly beneficial for studies of exchange bias.