Spin valve magnetoresistive sensor with self-pinned laminated layer and magnetic recording system using the sensor

A spin valve magnetoresistive sensor comprising:

• a substrate;
• a laminated self-pinned layer formed over the substrate and comprising first and second ferromagnetic films and an antiferromagnetically coupling film between the first and second ferromagnetic films for aligning the directions of magnetizations of the first and second ferromagnetic films to be generally antiparallel, the laminated layer having a net magnetic moment substantially less than the sum of the magnetic moments of the first and second ferromagnetic films;
• a nonmagnetic spacer layer formed on and in contact with the second ferromagnetic film of the self-pinned laminated layer;
• a free ferromagnetic layer formed on and in contact with the spacer layer and having its magnetization oriented generally perpendicular to the magnetizations of the first and second ferromagnetic films of the self-pinned laminated layer in the absence of an applied magnetic field;
• and
• wherein the sensor has no hard bias layer or exchange bias layer for pinning the magnetizations of the first or second ferromagnetic films in the self-pinned laminated layer;
• whereby in the presence of an applied magnetic field the magnetization of the free ferromagnetic layer rotates but the magnetic field energy generated in the laminated layer is insufficient to cause rotation of the magnetizations of the first or second ferromagnetic films and the magnetizations of the first and second ferromagnetic films remain self-pinned and antiparallel to one another.

A magnetic storage system comprising:

• a magnetic storage medium having a plurality of tracks for the recording of data;
• a magnetic transducer maintained close to the magnetic storage medium during relative motion between the magnetic transducer and the magnetic storage medium, the magnetic transducer including a spin valve magnetoresistive sensor comprising:
• first and second layers of ferromagnetic material separated by a spacer layer of nonmagnetic material, the magnetization direction of said first layer of ferromagnetic material being at an angle relative to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field, the second layer of ferromagnetic material comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of a magnetic field from the magnetic storage medium, the second ferromagnetic layer having a net magnetic moment substantially less than the sum of the magnetic moments of its first and second ferromagnetic films, wherein the sensor includes no hard bias layer or exchange bias layer for pinning the magnetization of the second ferromagnetic layer;
• and
• means coupled to the magnetoresistive sensor for detecting resistance changes in the magnetoresistive sensor responsive to magnetic fields representative of data bits recorded in the magnetic storage medium intercepted by the magnetoresistive sensor whereby in the presence of a magnetic field from the magnetic storage medium the magnetization of the first ferromagnetic layer rotates but the magnetic field energy generated in the second ferromagnetic layer is insufficient to cause rotation of the magnetizations of its first or second ferromagnetic films, and the magnetizations of the first and second ferromagnetic films thus remain self-pinned and antiparallel to one another.

A magnetic recording disk drive comprising:

• a magnetic recording disk;
• a motor connected to the disk for rotating the disk;
• a spin valve magnetoresistive sensor for sensing magnetically recorded data on the disk, the sensor comprising:
• a laminated self-pinned layer comprising first and second ferromagnetic films and an antiferromagnetically coupling film between the first and second ferromagnetic films for aligning the directions of magnetizations of the first and second ferromagnetic films to be generally antiparallel, the laminated self-pinned layer having a net magnetic moment substantially less than the sum of the magnetic moments of the first and second ferromagnetic films;
• a nonmagnetic spacer layer formed on and in contact with the second ferromagnetic film of the self-pinned laminated layer;
• a free ferromagnetic layer formed on and in contact with the spacer layer and having its magnetization oriented generally perpendicular to the magnetizations of the first and second ferromagnetic films of the self-pinned laminated layer in the absence of an applied magnetic field, the free ferromagnetic layer having a central sensing region and extensions on the sides of the central sensing region;
• a layer of an alloy comprising Fe and Mn formed on and in contact with each of the free ferromagnetic layer extensions for longitudinally biasing the magnetizations of the free layer extensions;
• and
• wherein the sensor has no hard bias layer or exchange bias layer for pinning the magnetizations of the first or second ferromagnetic films in the self-pinned laminated layer;
• whereby in the presence of an applied magnetic field from magnetically recorded data on the disk the magnetization of the free ferromagnetic layer rotates but the magnetic field energy generated in the laminated layer is insufficient to cause rotation of the magnetizations of the first or second ferromagnetic films in the laminated layer and the magnetizations of the first and second ferromagnetic films remain self-pinned and antiparallel to one another;
• a carrier supporting the spin valve magnetoresistive sensor and having a substrate onto which the sensor is attached;
• an actuator for moving the carrier generally radially across the disk so the sensor may access different regions of magnetically recorded data on the disk;
• means connecting the carrier to the actuator for maintaining the carrier near the disk;
• means electrically coupled to the sensor for detecting changes in resistance of the sensor in response to magnetic fields sensed by the sensor from the magnetically recorded disk;
• and
• means for supporting the motor and actuator.