Magnetoresistive stack without radiated field, sensor and magnetic mapping system comprising such a stack

A magnetoresistive stack comprising:

• a reference layer comprising:
• a first magnetic layer,
• a first antiferromagnetic layer in exchange coupling with the first magnetic layer,
• a second magnetic layer substantially of the same magnetisation as the first magnetic layer,
• a first non-magnetic spacer layer between the first magnetic layer and the second magnetic layer with a thickness enabling an antiferromagnetic RKKY coupling between the first magnetic layer and the second magnetic layer, said antiferromagnetic RKKY coupling having a first coupling intensity,
• a free layer having a coercivity lower than 10 microTesla, the free layer comprising:
• a third magnetic layer,
• a second antiferromagnetic layer in exchange coupling with the third magnetic layer,
• a fourth magnetic layer substantially of the same magnetisation as the third magnetic layer,
• a second non-magnetic spacer layer between the third magnetic layer and the fourth magnetic layer with a thickness enabling an antiferromagnetic RKKY coupling between the third magnetic layer and the fourth magnetic layer, said antiferromagnetic RKKY coupling having a second coupling intensity lower than the first coupling intensity, and
• a third non-magnetic spacer layer separating the reference layer and the free layer.