Abstract: One embodiment of the present invention is directed to a read head for a data storage device including a sensor for reading data from a data storage medium, a first shield disposed adjacent to the sensor and characterized as moment-compensated, and a second shield disposed adjacent to the sensor, the second shield being moment-compensated.

Abstract: One embodiment of the present invention is directed to a read head for a data storage device including a differential sensor for reading data from a data storage medium. The differential sensor includes a first and a second free layer. The magnetization of the free layers is anti-parallel. The read head also includes a first stabilization material disposed adjacent to the differential sensor. The first stabilization material includes a first hard magnet and a second hard magnet. The magnetization of the hard magnets is anti-parallel to each other. The read head also includes a second stabilization material disposed adjacent to the differential sensor. The second stabilization material includes a first hard magnet and a second hard magnet, wherein the magnetization of the hard magnets is anti-parallel to each other. The anti-parallel coupling of the first stabilization material and the second stabilization material enhances the anti-parallel magnetization of the free layers.

Abstract: A magnetic tunnel junction sensor is provided having a laminated free layer comprising a first sublayer formed of Co—Fe in contact with a spacer layer and a second sublayer formed of Ni—Fe—Mo. The Ni—Fe—Mo material of the second sublayer has a magnetocrystalline anisotropy constant, k, that is much smaller than that of Ni—Fe. Due to the small value of k of the Ni—Fe—Mo material used to fabricate the second sublayer of the free layer, the thickness of the Co—Fe first sublayer may be increased to improve manufacturability while retaining a low net stiffness of the free layer for high sensitivity of the MTJ sensor in response to signal fields from data magnetically recorded on a disk. The thicker Co—Fe first sublayer results in a higher magnetoresistance coefficient of the improved MTJ sensor.

Abstract: A spin valve transistor sensor is provided having a emitter element, a collector element and a common base element. The negatively biased emitter element injects a spin polarized hot electron current into the base element by tunneling from a ferromagnetic pinned layer to a ferromagnetic free layer through a first tunnel barrier layer. The positively biased collector element, comprising a second tunnel barrier layer and a nonmagnetic metal layer, collects the fraction of the hot electron current that passes through the base element and over the barrier height of the second tunnel barrier layer. The hot electron current is strongly spin polarized and due to the GMR effect in the magnetic tunnel junction element, the magnitude of the base-collector current is strongly dependent on external magnetic (signal) fields. A process is provided for fabrication of a spin valve transistor sensor suitable for high density magnetic recording applications.

Abstract: A dual hybrid magnetic tunnel junction (MTJ)/giant magnetoresistance (GMR) sensor is provided having an MTJ stack, a GMR stack and a common free layer. The MTJ stack includes a first antiferromagnetic (AFM) layer, an first antiparallel (AP)-pinned layer and a tunnel barrier layer. The GMR stack, operating in the current perpendicular to the plane (CPP) mode, includes a second AFM layer, a second AP-pinned layer and a spacer layer. The first and second AFM layers are set to pin the magnetizations of the first and second AP-pinned layers perpendicular to the ABS and in the same direction with respect to each other resulting in an additive response to a signal field of the MTJ and GMR stacks. The thickness of the spacer layer in the GMR stack is chosen to provide a negative ferromagnetic coupling field between the second AP-pinned layer and the free layer which opposes the positive ferromagnetic coupling field between the first AP-pinned layer and the free layer across the tunnel barrier layer.

Abstract: A spin valve (SV) magnetoresistive sensor is provided having an AP-pinned layer, a laminated ferromagnetic free layer and a non-magnetic electrically conductive spacer layer sandwiched between the AP-pinned layer and the free layer. The AP-pinned layer comprises first and second ferromagnetic layers separated by an antiparallel coupling (APC) layer. The laminated free layer comprises a third ferromagnetic layer of Co—Fe adjacent to the spacer layer and a fourth ferromagnetic layer of Co—Fe—Hf—O. The Co—Fe—Hf—O material of the fourth ferromagnetic layer has high resistivity resulting in reduced sense current shunting by the free layer. In addition, the metal oxide material of the fourth ferromagnetic layer is known to cause specular scattering of electrons. The reduced sense current shunting and the specular scattering of electrons both contribute to improving the GMR coefficient of the SV sensor.

Abstract: A differential magnetic tunnel junction (MTJ) sensor is provided having a first MTJ stack, a second MTJ stack and a common AP-coupled free layer. The AP-coupled free layer comprises a ferromagnetic first sense layer and a ferromagnetic second sense layer with an antiferromagnetic coupling (APC) layer disposed between the two sense layers providing strong antiferromagnetic coupling. The thickness of the first sense layer is chosen to be different (greater or smaller) than the thickness of the second sense layer so that the AP-coupled free layer has a net magnetic moment oriented parallel to the ABS and free to rotate in the presence of a signal magnetic field. Antiferromagnetic (AFM) layers in the first and second MTJ stacks are set to pin the magnetizations of pinned layers in each stack perpendicular to the ABS and in the same direction with respect to one another.

Abstract: An antiparallel (AP)-pinned spin valve (SV) sensor is provided which has positive and negative read signal symmetry about a zero bias point of a transfer curve upon sensing positive and negative magnetic incursions of equal magnitude from a moving magnetic medium. The SV sensor includes a ferromagnetic free layer which has a magnetic moment which is free to rotate in first and second directions from a position which corresponds to the zero bias point upon sensing positive and negative magnetic incursions, respectively, an AP-pinned layer, an antiferromagnetic layer which pins the magnetic moment of the AP-pinned layer along a pinned direction, and a spacer layer sandwiched between the AP-pinned layer and the free layer.

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.