Electrical and micromagnetic characterization of rotation sensors made from permalloy multilayered thin films

Planar Hall effect (PHE) measurements were performed on permalloy (Py)-based thin films and multilayered structures like FeMn/Py/Cu/Py. FeMn is used for pinning the magnetization of the adjacent Py layer by exchange biasing effect. Here, we present some results of our measurements made on square- and ring-shaped thin-film structures used as rotation sensors. At low magnetic fields, i.e., less than 200 Oe, we observed hysteretic effects and distortions from the expected sinusoidal shape of the angular dependence of the PHE voltage. This is due to hysteretic behaviour of the magnetic material and some coupling effects in the multilayered structure. In order to have a better understanding of this behaviour, micromagnetic simulations were performed to obtain the angular dependence of the sample magnetization for different intensities of the rotating magnetic field. To get better results, the film plane was divided into a number of single domains which interact between them and with the applied magnetic field.