Nanofabrication Methods Towards a Photonically-Based Torque Magnetometer for Measurement of Individual Single-Crystalline Yttrium-Iron-Garnet Microstructures

Abstract

This thesis describes preparation and nanofabrication of single crystalline yttrium-iron-garnet (YIG) for the purposes of ultra-clean torque magnetometry, as well as the design, fabrication, and testing of photonic crystal-based nanoelectromechanical systems for sensing applications. A focused ion beam microscope is used to shape and manipulate epitaxially grown YIG, a section of which was milled into a disk capable of supporting a 3-D vortex-like state. This was placed onto a prefabricated silicon torsional resonator, which allowed a broad characterization of magnetic and mechanical properties. Secondly, a photonic crystal-based sensor was designed in a silicon-on-insulator architecture and simulated with finite-difference time-domain methods. The final device properties were tested photonically and backed by further simulations. Once released, the mechanical properties of the system were characterized interferometrically, then photonically, showing the advantages to photonic based transduction schemes. The final device presents a platform for photonically studying magnetism, by use as a torque magnetometer.