Reorientation phase transition and sensitivity of the extraordinary Hall-effect-based sensors

Spin reorientation phase transition was observed in 5-10 nm thick polycrystalline Ni films at about 150 K. The extraordinary Hall effect resistivity in these films is enhanced by surface scattering and is of the order of 1 μΩ cm. Magnetization reversal in the vicinity of the transition is very sharp due to the development of the multi-domain structure with the out-of-plane anisotropy. As a result, the field sensitivity of the Hall resistance reaches values exceeding 500 Ω/T.