Magnetic and structural characterization of Fe-Ni films for high precision field sensing

In this paper, results are presented concerning structural and magnetic characterization of magnetic field sensing core Fe-Ni films utilizing super-paramagnetic-like rotation of magnetization on the film plane in order to minimize the magnetic noise and improve the system sensitivity. The rotating vector of magnetization was realized by transmitting sinusoidal and cosine fields on the film plane, having amplitude much larger than the anisotropy field of the film. Kerr microscopy studies and magnetoresistive measurements have been realized allowing the evaluation of the developed sensing cores. Furthermore XPS analysis helped in correlating the surface structure with the properties of the developed materials. In this way, the selected sensing cores have been tested with respect to the, applied field, illustrating acceptable levels of sensitivity and noise. Such an arrangement can be considered as promising for the development of new types of high precision monolithic CMOS compatible field sensors.