Anisotropic Magnetoresistive Sensors and Magnetometers Applying Alternating Bias Magnetic Field

Thin permalloy film with uniaxial anisotropy have been prepared by ion-beam sputtering method. Magnetic field sensors of this type film are composed of four magnetoresistors in Wheastone bridge connection. One may obtain sensitivity more than 10mV/Oe with 10^-5 Oe resolution by suitable design of sensors parameters. A model based on single domain structure and resistance anisotropy effect explains the behavior of the sensors and a method has been developed to reduce the influence of offset voltage and hysteresis to minimum.