Abstract: A magnetic tunnel junction (MTJ) device is usable as a magnetic field sensor in magnetic disk drives or as a memory cell in a magnetic random access (MRAM) array. The MTJ device has a "pinned" ferromagnetic layer whose magnetization is oriented in the plane of the layer but is fixed so as not to be able to rotate in the presence of an applied magnetic field in the range of interest, a "free" ferromagnetic layer whose magnetization is able to be rotated in the plane of the layer relative to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier layer located between and in contact with both ferromagnetic layers. The pinned ferromagnetic layer is pinned by interfacial exchange coupling with an adjacent antiferromagnetic layer. A high spin polarization ferromagnetic layer (Ni.sub.40 --Fe.sub.60) is placed near the tunnel barrier layer in both the pinned and free layers to enhance the magnetoresistive effect. The undesirable positive magnetostriction coefficient of the Ni.sub.

Abstract: An SV sensor having a reference (pinned) layer formed of a first high uniaxial anisotropy ferromagnetic material, such as Co--Fe, and a keeper layer formed of a second high uniaxial anisotropy ferromagnetic material, such as Ni--Fe--Nb. Lapping induced stress in the Co--Fe layer having high positive magnetostriction generates a stress-induced uniaxial anisotropy field in the reference layer resulting in enhanced reference layer magnetization. This uniaxial anisotropy field is capable by itself of maintaining a substantial transverse reference layer saturation even at elevated temperatures. Lapping induced stress in the Ni--Fe--Nb layer having high positive magnetostriction generates a stress-induced uniaxial anisotropy field in the keeper layer providing more uniform magnetization and therefore better flux cancellation. The high electrical resistivity of the Ni--Fe--Nb keeper layer has the further benefit of reducing sense current shunting by the keeper layer.

Abstract: An SV sensor having a reference (pinned) layer formed of a first high uniaxial anisotropy ferromagnetic material, such as Co--Fe, and a keeper layer formed of a second high uniaxial anisotropy ferromagnetic material, such as Ni--Fe--Nb. Lapping induced stress in the high positive magnetostriction Co--Fe layer generates a uniaxial anisotropy field in the pinned layer resulting in enhanced pinned layer magnetization. This uniaxial anisotropy field adds to the exchange field from an antiferromagnetic layer resulting in a substantially increased pinning field over the pinning field from the exhange interaction alone. The added uniaxial anisotropy field also improves the stability of the SV sensor at elevated temperatures since the uniaxial field is determined by a Curie temperature significantly higher than the blocking temperatures of antiferromagnetic materials.

Abstract: A method and apparatus in which on-chip functions are checked and any detected anomalies are located within a nested time interval. An on-chip function is tested by (1) applying a predetermined data pattern to the function, (2) computing a linear block error detection code residue from any output from the function being tested, and (3) comparing the residue to a error code residue (signature) derived from the output of a copy of the same function with the same data pattern. In one embodiment, the code signature has been previously derived from an error-free copy of the function. Where the signature is supplied contemporaneously by another copy of the same function also being tested, the function copy is not presumed error free. In both cases, any mismatch between the on-chip code residue and the signature indicates error, erasure, or fault. By either recursive reprocessing or shortening the intervals between comparisons, the mismatch can be located within a nested time or sequence interval.

Abstract: A method and apparatus for detecting harmful motion of a disk drive system to avoid a head crash. The motor spin current in the hard disk drive is used as a sensor to detect acceleration of the disk drive corresponding to a tipping or falling condition. In normal operation, the disk stack angular velocity (measured in revolutions per minute or RPM) is constantly monitored so that the disk drive control system can generate timing signals allowing the controller to accurately locate data addresses on the rotating disks. Disk stack RPM is accurately controlled at a constant value by a suitable feedback control loop which measures RPM and adjusts motor drive current to maintain the desired RPM. The rapidly rotating disk stack acts as a gyro system whose angular momentum resists any change in direction.

Abstract: A diaphragm isolator frame for supporting a disk drive in a rack or other enclosure while providing isolation from undesirable vibrations from other disk drives or components mounted in the enclosure or from the environment. The diaphragm isolator frame comprises a pair of side rails having isolators formed of thinned portions of the side rails to form diaphragms, each diaphragm having a centrally located press-pin for supporting the disk drive. The thickness and diameter of the diaphragms may be chosen to provide vibration isolation at a desired frequency.

Abstract: A magnetic tunnel junction (MTJ) device for use as a magnetic field sensor or as a memory cell in a magnetic random access (MRAM) array has one pinned ferromagnetic layer and one free ferromagnetic layer formed on opposite sides of an insulating tunnel barrier layer, and a hard biasing layer that is in proximate contact with and magnetostatically coupled to the free ferromagnetic layer. The magnetic tunnel junction in the sensor is formed on a first shield, which also serves as an electrical lead, and is made up of a stack of layers (MTJ stack). The layers in the MTJ stack are an antiferromagnetic layer, a pinned ferromagnetic layer, an insulating tunnel barrier layer, and a free ferromagnetic layer. The MTJ stack is generally rectangularly shaped with parallel side edges. A layer of hard biasing ferromagnetic material is in abutting contact to or overlapping the MTJ stack to longitudinally bias the magnetic moment of the free ferromagnetic layer in a preferred direction.

Abstract: A micromechanically fabricated read/write head for charge storage devices comprising a supporting base, a cantilever and a tip with a shaft and frontside end. The supporting base, cantilever and tip form one integral part made of electrically conducting material. The frontside end of the tip is so designed as to allow writing and reading of information in direct contact with the surface of a charge storage device. The shaft of the tip has a small diameter and is surrounded by a strengthening shell.

Abstract: An ion beam sputtering system having a chamber, an ion beam source, a multiple targets, a shutter, and a substrate stage for securely holding a wafer substrate during the ion beam sputtered deposition process in the chamber. The substrate stage is made to tilt about its vertical axis such that the flux from the targets hit the wafer substrate at a non-normal angle resulting in improved physical, electrical and magnetic properties as well as the thickness uniformity of the thin films deposited on the substrate in the ion beam sputtering system.

Abstract: A dual chamber deposition system comprising two ion beam sputtering (IBS) deposition chambers connected by a wafer handler chamber for depositions of multilayer thin film structures with improved process throughput. Reactive ion beam sputtering depositions and metal layer depositions on a substrate may be carried out in separate IBS deposition chambers while maintaining vacuum conditions throughout the process. A process for ion beam sputter deposition of spin valve (SV) magnetoresistive sensor layers having an AFM layer formed of NiO where reactive sputtering deposition of the NiO is carried out in a separate IBS deposition chamber from the subsequent metal layer depositions improves system throughput while maintaining SV sensor performance.

Abstract: A magnetoresistive (MR) sensor comprises a dual differential spin valve structure. Each of the spin valves comprise first (free) and second (pinned) layers of ferromagnetic material separated by a thin film layer of nonmagnetic material. The magnetization direction of the pinned layers of ferromagnetic material in each spin valve is fixed, and their magnetization is set antiparallel to each other. A current flow is produced through the MR sensor, and the variations in voltage across the MR sensor are sensed due to changes in resistance of the MR sensor produced by rotation of the magnetization in the free layers of ferromagnetic material as a function of the magnetic field being sensed.

Abstract: A magnetic tunnel junction (MTJ) device is usable as a magnetic field sensor in magnetic disk drives or as a memory cell in a magnetic random access (MRAM) array. The MTJ device has a ferromagnetic antiparallel (AP)-pinned layer comprising a first ferromagnetic layer, a second ferromagnetic layer and an antiparallel coupling (APC) layer disposed between the first and second ferromagnetic layers, a free ferromagnetic layer and an insulating tunnel barrier layer disposed between the first ferromagnetic layer of the AP-pinned layer and the free ferromagnetic layer. The magnetization of the AP-pinned layer is oriented in the plane of the layer but is fixed so as not to be able to rotate in the presence of an applied magnetic field in the range of interest. The magnetization of the free ferromagnetic layer is able to be rotated in the plane of the layer relative to the fixed magnetization of the ferromagnetic AP-pinned layer.

Abstract: A soft anti-parallel (AP)-pinned spin valve (SV) sensor comprising an AP-pinned layer separated from a ferromagnetic free layer by a non-magnetic electrically conducting spacer. The AP-pinned layer includes a first ferromagnetic pinned layer separated from a second ferromagnetic pinned layer by an anti-parallel coupling layer. The second pinned layer further includes a first and second ferromagnetic sub-layers. The first pinned layer which is the farthest pinned layer from the free layer is made of soft (low coercivity) magnetic material. The use of a low coercivity first pinned layer allows the magnetic field generated by the sense current to be used in setting the magnetizations directions of the pinned layer and reset the magnetization direction during the disk operation in the case that the magnetization direction becomes random.

Abstract: An AP-Pinned SV sensor with the preferred structure of NiO/Ni--Fe/Co/Ru/Co/Cu/Ni--Fe/Cap where the pinned layer comprises first and second ferromagnetic pinned layers separated from each other by an anti-parallel coupling layer. The first ferromagnetic pinned layer further comprises a first pinned sub-layer of Ni--Fe and a second pinned sub-layer of Co where the first pinned sub-layer of Ni--Fe is formed over and in direct contact with the NiO antiferromagnetic (AFM) layer. Addition of the first pinned sub-layer of Ni--Fe isolates the second pinned sub-layer of Co from the NiO AFM layer resulting in dramatic improvement in the pinning field and magnetic moment control of the laminated AP-pinned layer.

Abstract: A spin valve (SV) sensor having a Ni-Mn antiferromagnetic (AFM) layer, a pinned layer, a free layer and a spacer layer disposed between said free and pinned layers. The pinned layer is formed over and in contact with the antiferromagnetic (AFM) Ni-Mn layer where the combination of the AFM and pinned layers is first annealed before depositing the rest of the SV layers. Carrying out the annealing process of the combination of the AFM and pinned layers prior to deposition of the rest of the SV layers provides the exchange coupling field necessary to pin the pinned layer while avoiding thermal degradation of the SV sensor giant magnetoresistive effect.