DESIGN AND FABRICATION OF NANOMAGNETIC SENSORS BASED ON ELECTRODEPOSITED GMR MATERIALS

摘要

The operation of magnetic sensors is based on different physical principles, leading to the fabrication of different magnetic sensor types. Commercially available magnetic sensors such as Hall effect devices, inductive coil and fluxgate magnetometers have their own advantages and limitations. Magnetoresistive sensors are based on the change of the electric resistivity when they are subjected to a magnetic field. We introduce a low-cost method i.e. electrodeposition of magnetic multilayers, in order to fabricate sensitive magnetic sensors. We have successfully grown Co/Cu and Ni/Cu multilayers on n-type (100) Si substrate, from a single electrochemical electrolyte containing either both (Co~(+2) and Cu~(+2)) or both (Ni~(+2) and Cu~(+2)) ions, for growing Co/Cu and Ni/Cu multilayers respectively. While a maximum change of 12 percent was observed in the electric resistivity of the Co/Cu films when they were subjected to a magnetic field of 2000 Oe, the maximum change in resistivity for Ni/Cu multilayers was only 3.5 percent. Nevertheless, the sensitivity of multilayer Ni/Cu films in low magnetic fields (up to 100 Oe) was found to be almost twice that obtained for Co/Cu films.