Magnetic Sensors: AMR and GMR

This lecture covers the principles of Anisotropic Magnetoresistive (AMR) and Giant Magnetoresistive (GMR) sensors. AMR sensors use a 'soft' ferromagnetic strip to measure external magnetic fields, while GMR sensors consist of two ferromagnetic layers separated by a non-ferromagnetic conductor. The resistance in GMR sensors depends on the angle between the magnetization vectors. The lecture explains the 'chevron' geometry for AMR sensors, the sensitivity to weak magnetic fields, and the complex behavior around zero field. It also discusses Tunnel Magnetoresistance (TMR) sensors and their greater effect compared to GMR sensors. Applications and operating principles of these sensors are briefly described.