Optimized Soft Magnetic Electrodes for Ultra-Sensitive Magnetic Tunnel Junction Field Sensors

This SBIR project aims to develop a new class of low-field magnetic sensors based on magnetic tunnel junctions with magnesium oxide (MgO) tunnel barriers. The phase 1 effort aims to maximize the high-frequency sensitivity of the MgO-MTJ sensor devices by optimizing the magnetic characteristics of the free electrode. By using new and novel combinations of magnetic materials, in conjunction with proper post-deposition thermal magnetic treatments, the free layer's magnetic anisotropy will be greatly reduced, improving device sensitivity. We will develop improved annealing procedures to minimize the effects of interlayer magnetic coupling on the new sensor devices, and to linearize the sensor transfer curves. If suitable high-frequency noise characteristics are demonstrated, we will then be in a position to integrate the MgO-MTJ sensors with oscillating MEMS flux concentrators, currently in development, which will allow greatly improved noise performance (~1 pT/rtHz) at low frequencies.