An extraordinary magnetoresistance (EMR) sensor has an
antiferromagnetic/ferromagnetic exchange-coupled bilayer structure on top
of the EMR active film. The ferromagnetic layer in the bilayer structure
has perpendicular magnetic anisotropy and is exchange-biased by the
antiferromagnetic layer. The antiferromagnetic/ferromagnetic bilayer
structure provides a magnetic field perpendicular to the plane of the EMR
active film to bias the magnetoresistance vs. field response of the EMR
sensor. The ferromagnetic layer may be formed of any of the ferromagnetic
materials useful for perpendicular magnetic recording, and is prepared in
a way that its anisotropy axis is significantly out-of-plane. The
antiferromagnetic layer is formed of any of the known Mn alloys, such as
PtMn, NiMn, FeMn, IrMn, PdMn, PtPdMn and RhMn, or any of the insulating
antiferromagnetic materials, such as those based on the cobalt oxide and
nickel oxide antiferromagnetic materials.