A self-biased linear anisotropic magnetoresistance sensor realized by exchange biased bilayers

Abstract

A ferromagnetic/antiferromagnetic (FM/AFM) bilayers structure was proposed to act as a new structure to meet the demands of anisotropic magnetoresistance (AMR) linear sensor. Through a single domain model, we found that the direction of initial magnetic moment of FM layer could be modulated by the co-effect of the exchange bias (EB) field along vertical direction and the shape anisotropy field induced by limited regular size magnetic thin film. When the length and width of magnetic thin film are fixed, if a proper magnitude of EB field is adopted, the 45-degree self-biased AMR sensor can be achieved, and vice versa. Following the model, a series of Ta/NiFe/FeMn/Ta samples were grown by changing the EB field and shape anisotropy field, the self-biased sensor cell with high linearity and sensitivity was achieved.