Development of multilayered magnetic nanowires for giant magnetoresistive sensors

Switched reluctance motors (SRMs) are widely used for variable-speed applications due to their simplicity and ruggedness but their primary disadvantage is large torque ripple and they require complicated control techniques. One approach for reducing the torque pulsation is based on estimating the instantaneous torque in real-time and compensating with the motor drive power electronics. Flux density in the machine is directly measured by using embedded magnetic field sensors. The intent is to develop a fundamentally new approach to the design and operation of electric machines that will result in significantly improved efficiency and power density.;This dissertation describes the development of giant magnetoresistive (GMR) sensors with multilayered magnetic nanowires containing alternating ferromagnetic and nonmagnetic layers. Pulsed electrochemical deposition was used to control the periodic structure of multilayered nanoscale nanowires with preferential crystalline orientation. Co/Cu multilayered magnetic nanowires were grown through polymer nanopore membrane on substrates by lithography-assisted template bonding (LATB) method. Layer thicknesses and crystalline structure were varied and controlled to have an effect on the GMR results. Measurements and results of embedded GMR sensors in a prototype motor are also presented.