This creates an asymmetric electric field perpendicular to the current, which depends on the magnetization state of the sensor. Exactly controlling the magnetization state is the key to the operation of the planar Hall sensor. From fabrication the magnetization is confined to one certain direction in zero applied field, and the application of a field perpendicular to this direction changes the magnetization state in such a way that the electronic readout is linear with respect to the magnitude of the applied field.
This produces an uneven electric field at right angles to the current flow, which is influenced by the magnetic orientation of the sensor. The precise control of this magnetic state is crucial for the operation of the planar Hall sensor. From manufacturing, the magnetization is confined to a single direction in the absence of an external field, and introducing a perpendicular field causes the magnetization to change in such a way that the electronic readout is linear with respect to the applied field magnitude.