Novel Materials for Ultra-Sensitive Low-Frequency Magnetometers

In diverse application areas there is a need to develop magnetic field sensors which resolve small (nanoTesla-level) field perturbations at low (Hertz and milliHertz) frequencies. The emerging technology of spin-dependent tunneling is promising in that its attributes include low power, small size, low cost, IC compatibility (uses standard silicon microelectronics processing), and broad-band frequency resolution. The goal of this Phase II program is to increase the low-frequency signal-to-noise performance of magnetic tunnel junction devices (magnetic field sensors) by increasing the sensitivity and decreasing the intrinsic frequency-dependent excess noise. The central focus of the work involves the exploration and development of MgO as the tunnel barrier material. The proposed Phase II effort will involve multiple iterations of thin-film depositions, device fabrication, and comprehensive noise measurement and analysis. In addition to the major focus of materials-based noise reduction, a small parallel investigation will be made into a promising electronics noise filtering technique, especially appropriate for use with magnetic tunnel junctions. Results will be analyzed and the Phase II effort will culminate in the fabrication of ultra-sensitive, low-frequency, prototype magnetic field sensors.