The planar Hall sensor is a type of magnetic sensor based on the planar Hall effect of ferromagnetic materials. It measures the change in anisotropic magnetoresistance caused by an external magnetic field in the Hall geometry. As opposed to an ordinary Hall sensor, which measures field components perpendicular to the sensor plane, the planar Hall sensor responds to magnetic field components in the sensor plane. Generally speaking, for ferromagnetic materials, the resistance is larger when the current flows along the direction of magnetization than when it flows perpendicular to the magnetization vector. 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