Dual tunnel junction sensor with a single antiferromagnetic layer

A dual tunnel junction magnetic head, which has an air bearing surface (ABS) comprising:

• a dual tunnel junction read head that includes:
• a dual tunnel junction sensor responsive to applied magnetic fields;
• first and second electrically conductive lead layers connected to the tunnel junction sensor for conducting a tunnel current through the tunnel junction sensor;
• the dual tunnel junction sensor including:
• a ferromagnetic electrically conductive first shield layer;
• a ferromagnetic electrically conductive first free layer;
• an electrically conductive and magnetically isolating first isolation layer being located between the first shield layer and the first free layer;
• a ferromagnetic electrically conductive first pinned layer;
• a non-magnetic electrically insulating first barrier layer located between the first free layer and the first pinned layer;
• a ferromagnetic electrically conductive second pinned layer;
• an antiferromagnetic electrically conductive pinning layer located between the first and second pinned layers and exchange coupled to the pinned layers so as to pin the pinned layer magnetic moment in each of the pinned layers in a first direction;
• a ferromagnetic electrically conductive second free layer, the first and second free layers each having a magnetic moment in a second direction;
• a non-magnetic electrically insulating second barrier layer located between the second free layer and the second pinned layer;
• a ferromagnetic electrically conductive second shield layer;
• and
• an electrically conductive and magnetically isolating second isolation layer being located between the second free layer and the second shield layer;
• write head including:
• first and second pole piece layers and a write gap layer;
• the first and second pole piece layers being separated by the write gap layer at the ABS and connected at a back gap that is recessed rearwardly in the head from the ABS;
• an insulation stack having at least first and second insulation layers;
• at least one coil layer embedded in the insulation stack;
• and
• the insulation stack and the at least one coil layer being located between the first and second pole piece layers.

A magnetic disk drive that includes at least one dual tunnel junction magnetic head, which has an air bearing surface (ABS), the disk drive comprising:

• a dual tunnel junction read head that includes:
• a dual tunnel junction sensor that has a track width responsive to applied magnetic fields;
• first and second electrically conductive lead layers connected to the tunnel junction sensor for conducting a tunnel current through the tunnel junction sensor;
• the dual tunnel junction sensor including:
• a ferromagnetic electrically conductive first free layer;
• a ferromagnetic electrically conductive first pinned layer;
• a non-magnetic electrically insulating first barrier layer located between the first free layer and the first pinned layer;
• a ferromagnetic electrically conductive second pinned layer;
• an antiferromagnetic electrically conductive pinning layer located between the first and second pinned layers and exchange coupled to the pinned layers so as to pin the pinned layer magnetic moment in each of the pinned layers in a first direction;
• a ferromagnetic electrically conductive second free layer;
• a non-magnetic electrically insulating second barrier layer located between the second free layer and the second pinned layer;
• the first and second free layers each having a magnetic moment
• in a second direction;
• electrically conductive and magnetically isolating first and second isolation layers, the dual tunnel junction sensor being located between the first and second isolation layers;
• ferromagnetic electrically conductive first and second shield layers, the dual tunnel junction sensor with first and second isolation layers being located between the first and second shield layers;
• a write head including:
• first and second pole piece layers and a write gap layer;
• the first and second pole piece layers being separated by the write gap layer at the ABS and connected at a back gap that is recessed rearwardly in the head from the ABS;
• an insulation stack having at least first and second insulation layers;
• at least one coil layer embedded in the insulation stack;
• and
• the insulation stack and the at least one coil layer being located between
• the first and second pole piece layers;
• a housing;
• a magnetic disk rotatably supported in the housing;
• a support mounted in the housing for supporting the magnetic head with its ABS facing the magnetic disk so that the magnetic head is in a transducing relationship with the magnetic disk;
• means for rotating the magnetic disk;
• positioning means connected to the support for moving the magnetic head to multiple positions with respect to said magnetic disk;
• and
• processing means connected to the magnetic head, to the means for rotating the magnetic disk and to the positioning means for exchanging signals with the merged magnetic head, for controlling movement of the magnetic disk and for controlling the position of the magnetic head.

A method of making a dual tunnel junction read head that has an air bearing surface (ABS) comprising the steps of:

• forming a electrically conductive, magnetically isolating first isolation layer,
• forming a ferromagnetic electrically conductive first free layer on the first isolation layer;
• forming a non-magnetic electrically insulating first barrier layer on the first free layer;
• forming a ferromagnetic electrically conductive first pinned layer on the first barrier layer;
• forming an antiferromagnetic pinning layer on the first pinned layer;
• forming a ferromagnetic electrically conductive second pinned layer on the pinning layer;
• the pinning layer exchange coupled to the first and second pinned layers so as to pin the pinned layer magnetic moment in each of the pinned layers in a first direction;
• forming a second barrier layer on the second pinned layer;
• forming a ferromagnetic electrically conductive second free layer on the second barrier layer, the first and second free layers each having a magnetic moment in a second direction;
• and
• forming an electrically conductive, magnetically isolating second isolation layer on the second free layer.

A method of making a dual tunnel junction magnetic head that has an air bearing surface (ABS) comprising:

• forming a dual tunnel junction sensor that has a track width as follows:
• forming a ferromagnetic electrically conductive first shield layer;
• forming an electrically conductive, magnetically isolating first isolation layer on the first shield layer;
• forming a ferromagnetic electrically conductive first free layer on the first isolation layer;
• forming a non-magnetic electrically insulating first barrier layer on the first free layer;
• forming a ferromagnetic electrically conductive first pinned layer on the first barrier layer;
• forming an antiferromagnetic pinning layer on the first pinned layer;
• forming a ferromagnetic electrically conductive second pinned layer on the antiferromagnetic pinning layer;
• the pinning layer exchange coupled to the first and second pinned layers so as to pin the pinned layer magnetic moment in each of the pinned layers in a first direction;
• forming a second barrier layer on the second pinned layer;
• forming a ferromagnetic electrically conductive second free layer on the second barrier layer, the first and second free layers each having a magnetic moment in a second direction;
• forming an electrically conductive, magnetically isolating second isolation layer on the second free layer;
• and
• forming a second shield layer on the second isolation layer;
• forming a write head as follows:
• forming a first pole piece layer;
• forming a write gap layer and an insulation stack with a coil layer embedded therein;
• and
• forming a second pole piece layer on the insulation stack and the write gap and connected at a back gap to the first pole piece.