Giant Magnetoimpedance Effect In A Thin-Film Multilayer Meander-Like Sensor

A meander-like magnetic sensing element based on the giant magnetoimpedance (GMI) effect was prepared by using optical lithography and sputtering deposition techniques. The structure of the sensing element consists of layers of Permalloy (Py = Ni81Fe19), titanium (Ti), and copper (Cu) with composition [Py(100 nm)/Ti(6 nm)](4)/Cu(400 nm)/[Py(100 nm)/Ti(6 nm)](4). The GMI was investigated at room temperature under applied magnetic fields (H) varying in the range of +/- 4.0 kOe in both longitudinal and transversal geometries. The amplitude I-ac and frequency f of the ac electrical current were varied in the range of 0.35-6.50mA and 0.1-20 MHz, respectively. The overall dc electrical resistance of the sensing element was found to be 45.6 Omega. The sensing element yielded a GMI of 53.5% for H similar or equal to 5.0 Oe and f = 7.0 MHz, and the corresponding maximum average sensitivity of about 5 Omega/Oe. The sensing element was used for measuring the local Earth magnetic field (H-local = 0: 26 +/- 0.03 Oe) yielding a value close to the one measured by using a Hall sensor probe (= 0: 23 +/- 0.01 Oe). GMI sensors are being used in applications such as accelerometers, magnetometers, biomagnetism, magnetic compasses, traffic control, non-destructive analysis, and virus and cancer cell detection. Published by AIP Publishing.