| Angular dependencies are investigated for the planar Hall effect (PHE) in Permalloy (Ni80Fe20) thin films and Permalloy based multilayered structures used as rotation sensors in lab-on-a-chip applications. A distortion of the angular dependence symmetry with respect to the abscissa axis was observed. This is due to contacts misalignment, hysteresis behaviour of the magnetic material and some coupling effects in the multilayered structure. We performed micromagnetic simulations to discuss the effect of the magnetic field strength on the shape of the angular dependence of PHE. From experimental measurements and micromagnetic simulations, made on the multilayered structure, results a distortion of the angular dependence of the PHE for magnetic fields less than 16 kA/m (200 Oe) because the magnetization vector can not follow the direction of the applied magnetic field. Using a special setup in which we made PHE measurements over two orthogonal directions will give a rotation sensor with an improved symmetry of the output signal and an angular resolution bellow 0.5°. |
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