Effects of lateral dimensions of the magnetic thin films on the characteristics of thin-film type orthogonal fluxgate sensors

Orthogonal fluxgate sensors with Co-Nb-Zr magnetic thin films as the core material are fabricated using conventional photolithography and their performances characterized. The sensor structure consists of a central Cu thin film and surrounding Co-Nb-Zr magnetic layers. The magnetic layers are excited by an AC current applied along the Cu film, and the output voltage is detected with an external pickup coil surrounding the sensor. A DC bias current, sufficient to saturate the magnetic layers, is applied along the Cu film, thus allowing for the fundamental mode operation. The lateral dimensions of the magnetic thin films are the main parameters investigated, and are varied widely; the width is in the range 0.5-1.1 mm, and the length is in the range 1.6-9.6 mm. The device characteristics measured under the optimum conditions show that the output voltage is linear and the sensitivity is constant over a wide range of external magnetic field (- 2400 A/m-+ 2400 A/m). The normalized output voltage with respect to the magnetic area is high for a high aspect ratio and a small width of the magnetic thin films. The highest values of peak-to-peak output voltage and normalized output voltage achieved in this study are 14,120 mV and 2783 V/mm², respectively.