Magnetoresistive sensor based on the spin valve effect

A magnetoresistive sensing system comprising:

• a magnetoresistive sensor comprising a substrate and a layered structure formed on said substrate, the layered structure comprising a first and second thin film layer of ferromagnetic material separated by a thin film layer of non-magnetic metallic material, at least one of said layers of ferromagnetic material being formed of a material taken from the group consisting of cobalt and cobalt alloys, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field;
• means for producing a current flow through said magnetoresistive sensor;
• and
• means for sensing the variations in the resistivity of said magnetoresistive sensor due to the difference in rotation of the magnetizations in said layers of ferromagnetic materials as a function of the magnetic field being sensed.