Middle shields two-dimensional magnetic recording read heads
The present disclosure generally relates to a dual free layer two dimensional magnetic recording read head. The read head comprises a first lower shield, a first sensor disposed over the first lower shield, a first upper shield disposed over the first sensor, a read separation gap (RSG) disposed on the first upper shield, a second lower shield disposed over the RSG, a second sensor disposed over the second lower shield, and a second upper shield disposed over the second sensor. In some embodiments, the second lower shield comprises a CoFeHf layer. In another embodiment, the second lower shield is a synthetic antiferromagnetic multilayer comprising a first shield layer, a second shield layer, and a CoFe/Ru/CoFe anti-ferromagnetic coupling layer or a Ru layer disposed therebetween, the first and second shield layers comprising NiFe and CoFe. In yet another embodiment, the second lower shield comprises layers of Ru, IrMn, and NiFe.
1. A read head, comprising:
a first lower shield;
a first sensor disposed over the first lower shield;
a second sensor disposed over the first sensor, wherein a down-track spacing between the first sensor and the second sensor is about 75 nm to about 85 nm;
a first upper shield disposed over the second sensor; and
a middle shield disposed between the first sensor and the second sensor, the middle shield comprising:
a second upper shield disposed over the first sensor;
a read separation gap disposed on the second upper shield, wherein the second upper shield and the read separation gap are substantially planar, extending into the read head substantially perpendicular to a media facing surface (MFS);
a seed layer disposed on the read separation gap, the seed layer comprising a bilayer of Ru/NiFe, Ru/NiCr, SiO 2 /NiFe, or SiO 2 /NiCr, or a single layer of NiCr; and
a second lower shield disposed between the read separation gap and the second sensor, the second lower shield being a multilayer shield comprising a CoFe/Ru/CoFe anti-ferromagnetic coupling (AFC) layer or a Ru layer, wherein the second lower shield has a first thickness at the MFS and a second thickness recessed from the MFS, the first thickness being greater than the second thickness.
2. The read head of claim 1 , wherein the second lower shield further comprises a first shield layer and a second shield layer, the AFC layer or the Ru layer being disposed between the first shield layer and the second shield layer.
3. The read head of claim 2 , wherein the first shield layer and the second shield layer each individually comprises NiFe, CoFe, and combinations thereof.
4. The read head of claim 2 , wherein the second shield layer has a greater thickness than the first shield layer.
5. The read head of claim 2 , wherein the first shield layer has a thickness substantially equal to or smaller than the second shield layer.
6. The read head of claim 1 , wherein the second lower shield comprises the Ru layer, and wherein the second lower shield further comprises an antiferromagnetic (AFM) layer disposed on the Ru layer, and a pinned layer disposed on the AFM layer.
7. The read head of claim 6 , wherein a thickness of the AFM layer is greater than a thickness of the Ru layer, and wherein a thickness of the pinned layer is greater than the thickness of the AFM layer.
8. A magnetic recording device comprising the read head of claim 1 .
9. A read head, comprising:
a first lower shield;
a first dual free layer (DFL) sensor disposed over the first lower shield;
a second DFL sensor disposed over the first DFL sensor, wherein a down-track spacing between the first sensor and the second sensor is about 75 nm to about 85 nm;
a first upper shield disposed over the second DFL sensor; and
a substantially planar middle shield disposed between the first DFL sensor and the second DFL sensor, the substantially planar middle shield comprising:
a second upper shield disposed over the first DFL sensor;
a read separation gap disposed on the second upper shield, wherein the second upper shield and the read separation gap are substantially planar, extending into the read head substantially perpendicular to a media facing surface (MFS);
a seed layer disposed on the read separation gap, the seed layer comprising a bilayer of Ru/NiFe, Ru/NiCr, SiO 2 /NiFe, or SiO 2 /NiCr, or a single layer of NiCr; and
a second lower shield disposed between and in contact with the seed layer and the second DFL sensor, the second lower shield being a multilayer shield comprising:
a first shield layer disposed on the seed layer,
a CoFe/Ru/CoFe anti-ferromagnetic coupling (AFC) layer or a Ru layer disposed on the first shield layer, and
a second shield layer disposed on the AFC layer or the Ru layer, wherein the second lower shield has a first thickness at the MFS and a second thickness recessed from the MFS, the first thickness being greater than the second thickness.
10. The read head of claim 9 , wherein the first shield layer and the second shield layer are each an individually multilayer or single layer structure comprising NiFe, CoFe, and combinations thereof.
11. The read head of claim 9 , wherein a thickness of the AFC layer or the Ru layer is less than the thickness of the first shield layer.
12. The read head of claim 9 , wherein the AFC layer or the Ru layer has a thickness of about 8 Å, the first shield layer has a thickness of about 80 Å to about 160 Å, and the second shield layer has a thickness of about 160 Å to about 260 Å.
13. A magnetic recording device comprising the read head of claim 9 .