Development of magnetoresistive thin film sensor for magnetic field sensing applications

Recently, nano-dimensional magnetic thin film and multilayer structures have attracted a great deal of interest due to the possibility of unique and desirable magnetic properties. Our research into magnetic thin films is primarily focused on the growth and properties of such structures on Si to develop the magnetic sensors for field sensing applications. Thin films of permalloy (Ni81Fe19) were deposited on silicon substrates using Ultra High vacuum (UHV) sputtering system (∼ 5 × 10−9 mbar). To achieve the negligible hysteresis and high thermal stability of these films, the magnetic and structural properties were optimized by (1) varying thicknesses of magnetic films, and (2) post annealing at various temperatures. Optimized films were then patterned to study the device output characteristics to know about their sensitivity and we achieve the sensitive of the order 45 μV/G/V which is equivalent to any commercially available magnetic sensors. These anisotropic magnetoresistive (AMR) based sensors are very u...