Simple planar Hall effect based sensors for low-magnetic field detection

Magnetic field sensors based on the planar Hall effect using single layer Ni80Fe20thin films have been designed, fabricated and characterized. By optimizing the sensor's dimension, such as the thickness and the length to width ratio, experimental results have shown that the sensor's sensitivity could be increased up to three times thanks to the enhancement of the shape magnetic anisotropy. The highest sensitivity of 100 ?V Oe?1corresponding to the relative resistance change up to 20 m?/Oe was achieved at a supplied DC current of 5 mA for the cross-shaped geometry of the sensor with 5 nm in the thickness and a length/width ratio of 10. Simple structure, low fabrication cost, and low power consumption make this sensor very promising for low field magnetic field sensing such as geomagnetic field detections.