Abstract: A Lorentz magnetoresistive sensor that employs a gating voltage to control the momentum of charge carriers in a quantum well structure. A gate electrode can be formed at the top of the sensor structure to apply a gate voltage. The application of the gate voltage reduces the momentum of the charge carriers, which makes their movement more easily altered by the presence of a magnetic field, thereby increasing the sensitivity of the sensor.

Abstract: An electrical circuit structure employing graphene as a charge carrier transport layer. The structure includes a plurality of graphene layers. Electrical contact is made with one of the layer of the plurality of graphene layers, so that charge carriers travel only through that one layer. By constructing the active graphene layer within or on a plurality of graphene layers, the active graphene layer maintains the necessary planarity and crystalline integrity to ensure that the high charge carrier mobility properties of the active graphene layer remain intact.

Abstract: A slider for magnetic data recording having a semiconductor based magnetoresistive sensor such as a Lorentz magnetoresistive sensor formed on an air bearing surface of the slider body. The slider is constructed of Si, which advantageously provides a needed physical robustness as well being compatible with the construction of a semiconductor based sensor thereon. A series of transition layers are provided between the surface of the Si slider body and the semiconductor based magnetoresistive sensor in order to provide a necessary grain structure for proper functioning of the sensor. The series of transition layers can be constructed of layers of SiGe each having a unique concentration of Ge.

Abstract: A Lorenz magnetoresistive sensor having a pair of voltage leads and a pair of current leads. The voltage leads are located at either side of one of the current leads and are separated by a distance that is substantially equal to the length of a bit to be measured. The Lorenz magnetoresistive sensor can be, for example an extraordinary magnetoresistive sensor having a quantum well structure such as a two dimensional electron gas and a shunt structure formed on an edge of the quantum well structure opposite the voltage and current leads.

Abstract: A perpendicular recording medium having an underlayer structure that improves the microstructural properties of the recording layer. A spacer layer is intercalated between the lower and upper hcp metal layers. This results in improvements in microstructure of the upper hcp metal layer and the recording magnetic layer, which in turn results in gains in recording media performance. Further, the thickness of the upper hcp metal layer can be reduced, thereby reducing the distance between the recording layer and the soft underlayer, providing further gains in recording media performance.

Abstract: A perpendicular magnetic recording disk has a granular cobalt alloy recording layer (RL) containing an additive oxide or oxides, an intermediate layer (IL) as an exchange-break layer on the “soft” magnetic underlayer (SUL), and an ultrathin nucleation film (NF) between the IL and the RL. In the method of making the disk, the IL is deposited at a relatively low sputtering pressure, to thereby reduce the roughness of the RL and overcoat (OC), while the NF and RL are deposited at substantially higher sputtering pressures. The resulting disk has good recording properties and improved corrosion resistance over a comparable disk made with an IL deposited at high sputtering pressure and without the NF. The NF may be a discontinuous film with an average thickness of less than about 1 nm.

Abstract: A magnetic storage system according to one embodiment includes magnetic media containing magnetic domain tracks; and at least one head for reading from the magnetic media, each head having: a first Extraordinary Magentoresistive (EMR) device for detecting magnetic fields of a first magnetic domain track; a second EMR device for detecting magnetic fields of a second magnetic domain track. The system further includes a slider for supporting the head; and a control unit coupled to the head for controlling operation of the head. A system according to another embodiment includes a first Extraordinary Magnetoresistive (EMR) device for detecting magnetic fields of a magnetic domain of interest. A system according to yet another embodiment includes an Extraordinary Magnetoresistive (EMR) device for deriving servoing information.

Abstract: A device employing a quantum well structure having a pattern that is defined by a photolithographically patterned top gate electrode. By defining the active area of the quantum well structure by the patterning of the top gate electrode there is no need to pattern the quantum well structure itself, such as by etching or other processes. This advantageously allows the active are of the quantum well structure to be patterned to a very small size, without the damaging edge effects associated with the patterning of the quantum well structure itself.

Abstract: Methods of fabricating perpendicular magnetic recording media are disclosed. The multilayer structures of the perpendicular magnetic recording media are fabricated by varying the sputtering conditions (i.e., pressure, sputtering gas, etc) in a single sputtering module so that multiple sputtering modules are not needed to form the multilayer structures. These fabrication methods allow sputtering tools with a limited number of chambers, which were designed for the manufacture of longitudinal media, to be used to efficiently produce perpendicular media architectures which heretofore required a large number of sputtering modules. It is further shown that media structures involving a geometric weak-link architecture are suited for these fabrication techniques.

Abstract: A Lorentz Magnetoresistive sensor having an ultrathin trapping layer disposed between a quantum well structure and a surface of the sensor. The trapping layer prevents charge carriers from the surface of the sensor from affecting the quantum well structure. This allows the quantum well structure to be formed much closer to the surface of the sensor, and therefore, much closer to the magnetic field source, greatly improving sensor performance. A Lorentz Magnetoresistive sensor having a top gate electrode to hinder surface charge carriers diffusing into the quantum well, said top gate electrode being either a highly conductive ultrathin patterned metal layer or a patterned monoatomic layer of graphene.

Abstract: An integrated servo and read device implementing Extraordinary Magnetoresistive (EMR) sensors. In one embodiment, dedicated EMR sensors are employed: one for data reading and one for servo operations. The sensors are preferably configured in an abutted configuration. In addition to magnetic recording systems, the device is also useful in a magnetic imaging device such as a scanning magnetometer. The integrated device may also be useful in other devices requiring a high sensitivity, high resolution sensor.

Abstract: A Lorentz magnetoresistive sensor having integrated signal amplification. The sensor is constructed upon a substrate such as a semiconductor material, and an amplification circuit such as transistor is constructed directly into the substrate on which the magnetoresistive device is constructed. This integrated signal amplification greatly enhances sensor performance by eliminating a great deal of signal noise that would otherwise be added to the read signal.

Abstract: An Extraordinary Magnetoresistive Sensor (EMR Sensor) having wide voltage lead tabs for reduced noise and increased signal to noise ratio. The leads can be formed in a triad structure, wherein a pair of voltage leads is located at either side of a current lead, or can be formed in a diad structure having a single voltage lead located at one side of a current lead.

Abstract: A Lorentz Magnetoresistive sensor having an extremely small lead width and lead spacing is disclosed. The sensor can be constructed by a novel fabrication method that allows the leads to be deposited in such a manner that lead width and spacing between the leads is determined by the as deposited thicknesses of the lead layers and electrically insulating spacer layers between the leads rather than by photolithography. Because the lead thicknesses and lead spacings are not defined photolithograhically, the lead thickness and lead spacing are not limited by photolithographic resolution limits.

Abstract: A contact magnetic transfer (CMT) master template with antiferromagnetically-coupled (AF-coupled) magnetic islands is used for transferring a magnetic pattern, such as a servo pattern, to a magnetic recording disk. The template is a rigid or flexible substrate with each magnetic island being two ferromagnetic films antiferromagnetically-coupled by an antiferromagnetically-coupling (AFC) film. In the presence of the applied magnetic field the magnetic moments of the two ferromagnetic films are parallel and substantially identical so they generate a magnetic field that cancels the applied field in the region of the slave disk facing the islands. However, when the applied field is removed, any residual magnetization results in the remanent moments in the two ferromagnetic films being oriented antiparallel as a result of the antiferromagnetic exchange coupling across the AFC film. Thus the islands have no net remanent magnetic moment that can affect the servo pattern transferred to the recording disk.

Abstract: An extraordinary magnetoresistive device EMR sensor that is capable of reading two separate tracks of data simultaneously. The EMR sensor has a semiconductor structure with an electrically conductive shunt structure at one side. The other side of the semiconductor structure is connected with a pair of current leads. Each of the current leads is disposed between a pair of voltage leads. Each pair of voltage leads is capable of independently reading a magnetic signal by measuring the voltage potential change across the pair of voltage leads. The EMR structure minimizes the number of leads needed to read two magnetic signals by using a single pair of current leads to read two tracks of data.

Abstract: A system method and apparatus for determining a position error signal (PES) for servo tracking in a data recording system using a data track. The PES is determined using a sensor array that includes a plurality of sensors offset from one another by certain predetermined distances in a direction perpendicular to the track direction. Correlation functions can be determined for pairs of sensors in the sensor array based on the signals read by the sensors. The results of these correlation functions can then be used to determine a PES by using a look up table or computational processor.

Abstract: A patterned perpendicular magnetic recording medium has discrete magnetic islands, each of which has a recording layer (RL) structure that comprises two exchange-coupled ferromagnetic layers. The RL structure may be an “exchange-spring” RL structure with an upper ferromagnetic layer (MAG2), sometimes called the exchange-spring layer (ESL), ferromagnetically coupled to a lower ferromagnetic layer (MAG1), sometimes called the media layer (ML). The RL structure may also include a coupling layer (CL) between MAG1 and MAG2 that permits ferromagnetic coupling. The interlayer exchange coupling between MAG1 and MAG2 may be optimized, in part, by adjusting the materials and thickness of the CL. The RL structure may also include a ferromagnetic lateral coupling layer (LCL) that is in contact with at least one of MAG1 and MAG2 for mediating intergranular exchange coupling in the ferromagnetic layer or layers with which it is in contact (MAG2 or MAG1).

Abstract: An extraordinary magnetoresistive sensor (EMR sensor) having reduced size and increased resolution is described. The sensor includes a plurality of electrically conductive leads contacting a magnetically active layer and also includes an electrically conductive shunt structure. The electrically conductive leads of the sensor and the shunt structure can be formed in a common photolithographic masking and etching process so that they are self aligned with one another. This avoids the need to align multiple photolithographic processing steps, thereby allowing greatly increased resolution and reduced lead spacing. The EMR sensor can be formed with a magnetically active layer that can be close to or at the air bearing surface (ABS) for improved magnetic spacing with an adjacent magnetic medium of a data recording system.

Abstract: A magnetic head has a sensor which employs the “Hall effect”. In one illustrative example, the sensor includes a generally planar body made of a semiconductor heterostructure; first and second contacts comprising first and second drains, respectively, which are formed over a first end of the body and spaced equally apart from a centerline of the body; and a third contact comprising a source formed over a second end of the body which is opposite the first end of the body. The semiconductor heterostructure is comprised of a high mobility two-dimensional electron or hole gas close to an air bearing surface (ABS) of the magnetic head so as to be exposed to magnetic field lines substantially normal to it from magnetically recorded bits. Advantageously, the sensor does not require magnetic materials utilized in conventional sensors and therefore does not suffer from magnetic noise associated therewith.