Nanomechanical Torque Magnetometry and AC Susceptometry of Mesoscopic Magnetic Structures

Abstract

Nanomechanical torque magnetometry is emerging to become one of the most highly-sensitive methods for measuring magnetostatic interactions in mesoscopic magnetic materials. Here, advances in torque magnetometry are offered for the probing of new physics and extending the functionality of the devices to explore phenomena previously inaccessible using the technique. In early studies, fully magnetic cantilevers were fabricated and the magnetization switching along the length of the devices was mechanically characterized using a simple model to describe the cantilever deflection under the influence of a magnetic torque. Torsional magnetometers were later primarily investigated due to their high responsivity to a magnetic torque applied along the torsion rod axis. A method for the calibration of a torque magnetometer's displacement and magnetic moment sensitivity, through the detection of thermomechanical noise is offered. A vector-based nanomechanical transduction scheme was later developed to investigate the pristine internal three dimensional magnetization present in a micromachined yttrium iron garnet disk. Finally, a new method for the simultaneous detection of DC magnetization and low-frequency AC susceptibility was developed, bringing nanomechanical magnetometry toward the realm of magnetization dynamics.