Magnetic read sensors having stabilized upper readers, and related methods

A magnetic device, comprising:

• a first sensor comprising:
• a lower shield,
• a magnetic seed layer disposed above the lower shield;
• a first lower free layer disposed above the magnetic seed layer,
• a second lower free layer disposed above the first lower free layer,
• a second shield disposed above the second lower free layer, and
• a first antiferromagnetic (AFM) layer disposed above the second shield;
• an insulating separation layer disposed above the first AFM layer;
• and
• a second sensor comprising:
• a magnetic seed layer disposed above the insulating separation layer,
• a second antiferromagnetic (AFM) layer disposed between the magnetic seed layer of the second sensor and the insulating separation layer to pin the magnetic seed layer of the second sensor,
• a cap layer,
• a first upper free layer disposed between the cap layer and the magnetic seed layer of the second sensor,
• a second upper free layer disposed between the first upper free layer and the cap layer,
• an upper shield disposed above the cap layer, and
• a third AFM layer disposed above the upper shield, wherein each of the first AFM layer, the second AFM layer, and the third AFM layer is magnetized in the same magnetization direction.

A read head for magnetic recording devices, comprising:

• a first reader comprising:
• a lower shield,
• a first lower free layer disposed above the lower shield,
• a second lower free layer disposed above the first lower free layer, and
• a second shield disposed above the second lower free layer;
• an insulating separation layer disposed above the first reader;
• and
• a second reader, the second reader comprising:
• a magnetic seed layer disposed above the insulating separation layer, the magnetic seed layer comprising a platform protruding in a downtrack direction,
• a plurality of first soft bias side shields disposed above the magnetic seed layer,
• a plurality of second soft bias side shields disposed above the plurality of first soft bias side shields,
• a plurality of spacer layers between the plurality of first soft bias shields and the plurality of second soft bias side shields,
• an antiferromagnetic (AFM) layer disposed between the magnetic seed layer and the insulating separation layer to pin the magnetic seed layer,
• a cap layer,
• a first upper free layer disposed between the magnetic seed layer and the cap layer,
• a second upper free layer disposed between the first upper free layer and the cap layer,
• a barrier layer disposed between the first upper free layer and the second upper free layer, and
• an upper shield disposed above the cap layer, wherein the magnetic seed layer is pinned such that the magnetic seed layer is magnetized in the same magnetization direction as one or more of the upper shield or the plurality of second soft bias side shields.