Giant magnetoresistive sensor with a high resistivity free layer

A spin valve (SV) magnetoresistive sensor, comprising:

• an antiferromagnetic (AFM) layer;
• an antiparallel (AP)-pinned layer adjacent to said AFM layer, said AP-pinned layer comprising;
• a first ferromagnetic layer adjacent to said AFM layer;
• a second ferromagnetic layer;
• and
• an antiparallel coupling (APC) layer disposed between said first ferromagnetic layer and said second ferromagnetic layer;
• a ferromagnetic free layer comprising;
• a third ferromagnetic layer;
• and
• a fourth ferromagnetic layer of high electrical. resistivity material adjacent to said third ferromagnetic layer, wherein said fourth ferromagnetic layer is made of Co—Fe—Hf—O;
• and
• a spacer layer of nonmagnetic electrically conductive material disposed between said second ferromagnetic layer and said third ferromagnetic layer.

A magnetic read/write head comprising:

• a write head including:
• at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack;
• first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS);
• the insulation stack being sandwiched between the first and second pole piece layers;
• and
• a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS;
• a read head including:
• a spin valve (SV) magnetoresistive sensor, comprising:
• an antiferromagnetic (AFM) layer;
• an antiparallel (AP)-pinned layer adjacent to said AFM layer, said AP-pinned layer comprising;
• first ferromagnetic layer adjacent to said AFM layer;
• a second ferromagnetic layer;
• and
• an antiparallel coupling (APC) layer disposed between said first ferromagnetic layer and said second ferromagnetic layer;
• a ferromagnetic free layer comprising;
• a third ferromagnetic layer;
• and
• a fourth ferromagnetic layer of high electrical resistivity material adjacent to said third ferromagnetic layer, wherein said fourth ferromagnetic layer is made of Co—Fe—Hf—O;
• and
• a spacer layer of nonmagnetic electrically conductive material disposed between said second ferromagnetic layer and said third ferromagnetic layer;
• and
• an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head.

A disk drive system comprising:

• a magnetic recording disk;
• a magnetic read/write head for magnetically recording data on the magnetic recording disk and for sensing magnetically recorded data on the magnetic recording disk, said magnetic read/write head comprising:
• a write head including:
• at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack;
• first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS);
• the insulation stack being sandwiched between the first and second pole piece layers and
• a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS;
• a read head including:
• a spin valve (SV) magnetoresistive sensor comprising:
• an antiferromagnetic (AFM) layer;
• an antiparallel (AP)-pinned layer adjacent to said AFM layer, said AP-pinned layer comprising;
• a first ferromagnetic layer adjacent to said AFM layer;
• a second ferromagnetic layer;
• and
• an antiparallel coupling (APC) layer disposed between said first ferromagnetic layer and said second ferromagnetic layer;
• a ferromagnetic free layer comprising;
• a third ferromagnetic layer;
• and
• a fourth ferromagnetic layer of high electrical resistivity material adjacent to said third ferromagnetic layer, wherein said fourth ferromagnetic layer is made of Co—Fe—Hf—O;
• and
• a spacer layer of nonmagnetic electrically conductive material disposed between said second ferromagnetic layer and said third ferromagnetic layer;
• and
• an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head;
• an actuator for moving said magnetic read/write head across the magnetic disk so that the read/write head may access different regions of the magnetic recording disk;
• and
• a recording channel coupled electrically to the write head for magnetically recording data on the magnetic recording disk and to the SV sensor of the read head for detecting changes in resistance of the SV sensor caused by rotation of the magnetization axis of the AP-coupled free layer relative to the fixed magnetizations of the first and second pinned layers in response to magnetic fields from the magnetically recorded data.