Magnetoresistive sensor with antiferromagnetic exchange-coupled structure formed by use of chemical-ordering enhancement layer

A magnetoresistive read head for sensing data recorded on a magnetic recording medium in the presence of sense current through the head, the head comprising:

• a substrate;
• a free ferromagnetic layer having a magnetization direction oriented substantially parallel to the plane of the recording medium in the absence of an external magnetic field, said free layer magnetization direction being substantially free to rotate in the presence of magnetic fields from the recording medium;
• a nonmagnetic spacer layer on the free ferromagnetic layer;
• and
• an exchange-coupled structure comprising (a) a pinned ferromagnetic layer on the spacer layer and having a magnetization direction oriented substantially perpendicular to the plane of the recording medium and substantially prevented from rotating in the presence of magnetic fields from the recording medium;
• (b) an antiferromagnetic layer exchange-coupled with the pinned ferromagnetic layer and formed of a substantially-chemically-ordered alloy comprising X and Mn and having a tetragonal crystalline structure, wherein X is selected from the group consisting of Pt, Ni, Ir, Pd and Rh;
• and (c) a chemically-ordering enhancement layer in contact with the antiferromagnetic layer and formed of a substantially-chemically-ordered alloy having a tetragonal crystalline structure, the enhancement layer alloy selected from the group consisting of alloys of AuCu, FePt, FePd, AgTi3, Pt Zn, PdZn, IrV, CoPt and PdCd.

A magnetoresistive read head for sensing data recorded on a magnetic recording medium in the presence of sense current through the head, the head comprising:

• a substrate;
• a free ferromagnetic layer on the substrate and having a magnetization direction oriented substantially parallel to the plane of the recording medium in the absence of an external magnetic field, said free layer magnetization direction being substantially free to rotate in the presence of magnetic fields from the recording medium;
• an exchange-coupled structure on the substrate and comprising (a) a pinned ferromagnetic layer having a magnetization direction oriented substantially perpendicular to the plane of the recording medium and substantially prevented from rotating in the presence of magnetic fields from the recording medium, and (b) an antiferromagnetic layer exchange-coupled with the pinned ferromagnetic layer and formed of a substantially-chemically-ordered alloy comprising Pt and Mn and having a tetragonal crystalline structure, the thickness of the PtMn alloy antiferromagnetic layer being less than approximately 125 Angstroms;
• and
• a nonmagnetic spacer layer between the free ferromagnetic layer and the pinned ferromagnetic layer.