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: 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.

Abstract: A structure for preventing Electrostatic Discharge (ESD) damage to a magnetoresistive sensor during manufacture. The structure includes a switching element that can be switched off during testing of the sensor and then switched back on to provide ESD shunting to the sensor. The switch can be a thermally activated mechanical relay built onto the slider. The switch could also be a programmable resistor that includes a solid electrolyte sandwiched between first and second electrodes. One of the electrodes functions as an anode. When voltage is applied in a first direction an ion bridge forms across through the electrolyte across electrodes making the resistor conductive. When a voltage is applied in a second direction, the ion bridge recedes and the programmable resistor becomes essentially non-conductive.

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: An extraordinary magnetoresistive sensor having optimal magnetic sensitivity capable of reading a very narrow and short magnetic bit. The sensor includes a layer of semiconductor layer and a layer of electrically conductive material. The first and second leads are electrically connected with an edge of the semiconductor material, one of the leads being located a distance inward from an end of the sensor. The sensor also includes first and second voltage leads, located on either side of and close to one of the current leads.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: An exchange-coupled magnetic structure of a cobalt-ferrite layer adjacent a magnetic metal layer is used in magnetorestive sensors, such as spin valves or tunnel junction valves. The exchange-coupled magnetic structure is used in a pinning structure pinning the magnetization of a ferromagnetic pinned layer, or in an AP pinned layer. A low coercivity ferrite may be used in an AP free layer. Cobalt-ferrite layers may be formed by co-sputtering of Co and Fe in an oxygen/argon gas mixture, or by sputtering of a CoFe2 composition target in an oxygen/argon gas mixture. Alternatively, the cobalt-ferrite layer may be formed by evaporation of Co and Fe from an alloy source or separate sources along with a flux of oxygen atoms from a RF oxygen atom beam source. Magnetoresistive sensors including cobalt-ferrite layers have small read gaps and produce large signals with high efficiency.

Abstract: A magnetoresistive (MR) sensor can be shaped using ion beam irradiation and/or implantation through a mask introduced between a MR structure and an ion source. The mask covers selected portions of the MR structure to define the track width of the sensor. Ion irradiation and/or implantation reduces the magnetoresistance of the unmasked portions while leaving the masked portion substantially unaltered. The mask can be a photoresist mask, an electron beam resist mask, or a stencil mask. Alternatively the mask may be part of a projection ion beam system. Track width resolution is determined at the mask production step. The edges of the sensor can be defined by a highly collimated ion beam producing an extremely straight transition edge, which reduces sensor noise and improves sensor track width control. Improved hard bias layers that directly abut the sensor may be used to achieve a suitable stability. A variety of longitudinal bias schemes are compatible with ion beam patterning.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: A magnetoresistive (MR) sensor can be shaped using ion beam irradiation and/or implantation through a mask introduced between a MR structure and an ion source. The mask covers selected portions of the MR structure to define the track width of the sensor. Ion irradiation and/or implantation reduces the magnetoresistance of the unmasked portions while leaving the masked portion substantially unaltered. The mask can be a photoresist mask, an electron beam resist mask, or a stencil mask. Alternatively the mask may be part of a projection ion beam system. Track width resolution is determined at the mask production step. The edges of the sensor can be defined by a highly collimated ion beam producing an extremely straight transition edge, which reduces sensor noise and improves sensor track width control. Improved hard bias layers that directly abut the sensor may be used to achieve a suitable stability. A variety of longitudinal bias schemes are compatible with ion beam patterning.

Abstract: An exchange-coupled magnetic structure of a cobalt-ferrite layer adjacent a magnetic metal layer is used in magnetorestive sensors, such as spin valves or tunnel junction valves. The exchange-coupled magnetic structure is used in a pinning structure pinning the magnetization of a ferromagnetic pinned layer, or in an AP pinned layer. A low coercivity ferrite may be used in an AP free layer. Cobalt-ferrite layers may be formed by co-sputtering of Co and Fe in an oxygen/argon gas mixture, or by sputtering of a CoFe2 composition target in an oxygen/argon gas mixture. Alternatively, the cobalt-ferrite layer may be formed by evaporation of Co and Fe from an alloy source or separate sources along with a flux of oxygen atoms from a RF oxygen atom beam source. Magnetoresistive sensors including cobalt-ferrite layers have small read gaps and produce large signals with high efficiency.

Abstract: A magnetoresistive (MR) sensor can be shaped using ion beam irradiation and/or implantation through a mask introduced between a MR structure and an ion source. The mask covers selected portions of the MR structure to define the track width of the sensor. Ion irradiation and/or implantation reduces the magnetoresistance of the unmasked portions while leaving the masked portion substantially unaltered. The mask can be a photoresist mask, an electron beam resist mask, or a stencil mask. Alternatively the mask may be part of a projection ion beam system. Track width resolution is determined at the mask production step. The edges of the sensor can be defined by a highly collimated ion beam producing an extremely straight transition edge, which reduces sensor noise and improves sensor track width control. Improved hard bias layers that directly abut the sensor may be used to achieve a suitable stability. A variety of longitudinal bias schemes are compatible with ion beam patterning.

Abstract: An exchange-coupled magnetic structure of a cobalt-ferrite layer adjacent a magnetic metal layer is used in magnetorestive sensors, such as spin valves or tunnel junction valves. The exchange-coupled magnetic structure is used in a pinning structure pinning the magnetization of a ferromagnetic pinned layer, or in an AP pinned layer. A low coercivity ferrite may be used in an AP free layer. Cobalt-ferrite layers may be formed by co-sputtering of Co and Fe in an oxygen/argon gas mixture, or by sputtering of a CoFe2 composition target in an oxygen/argon gas mixture. Alternatively, the cobalt-ferrite layer may be formed by evaporation of Co and Fe from an alloy source or separate sources along with a flux of oxygen atoms from a RF oxygen atom beam source. Magnetoresistive sensors including cobalt-ferrite layers have small read gaps and produce large signals with high efficiency.

Abstract: A CPP magnetoresistive sensor with a spacer layer made of a heterogeneous material, which is composed of conductive grains within a highly resistive matrix, has a high resistance. The conductive grains are typically made of a conductive element or alloy that can operate as a GMR spacer material. The highly resistive matrix is typically made of a highly resistive or insulating element, alloy or compound that will hinder the flow of electrons. The sensing electrical current is passed through the conductive grains, which are typically made of the same material as GMR spacers, so the GMR is maintained even though the overall resistance is increased.

Abstract: A method for writing data on a magnetic recording medium includes providing a magnetic recording layer having at least two ferromagnetic films antiferromagnetically coupled together across a nonferromagnetic spacer film, with one of the ferromagnetic films having a greater magnetic moment than the other. A positive write field is applied to a first region to align the moments of both ferromagnetic films with the positive field, and then a negative write field is applied to an adjacent region to align the moments of both ferromagnetic films with the negative field. When the medium is moved away from the write fields, the moment of the ferromagnetic film with the lesser moment in each region flips to be antiparallel to the moment of the other ferromagnetic film in its region. The result is that the adjacent regions become adjacent magnetized domains with the transition between the domains representative of the written data.

Abstract: In a spin valve, at least one AP pinned sublayer and/or one AP free sublayer comprise high resistivity alloys of the type AB, wherein A is selected from the group consisting of CoFe, NiFe, and CoFeNi, and B is selected from the group consisting of B, Ta, Nb, Zr, and/or Hf. The resistivity value of the highly resistive layer is typically between about 30 &mgr;&OHgr;-cm and 100 &mgr;&OHgr;-cm. The highly resistive layers reduce the shunting of the sense current away from the rest of the structure, and prevent electrons from being shunted away from the active region of the spin valve and, thus, reducing &Dgr;R/R. The spin valve of this layered structure can increase the overall sheet resistance and optimize the &Dgr;R/R value of the spin valve.

Abstract: A magnetic sensor which detects an external magnetic field with the aid of a ferromagnetic free layer having a magnetic moment responsive to the external magnetic field. The magnetic sensor has an antiferromagnetic layer which is magnetically exchange-coupled to the free layer to produce an exchange bias field He which acts on the free layer to bias its magnetic moment along a certain orientation such as the transverse direction. The additional exchange bias field He is used in balancing a total transverse internal magnetic field Ht which is due to other fields generated by the sensor itself. The value of exchange bias field He is set, e.g., by selecting a certain thickness and a certain composition of the antiferromagnetic layer. The magnetic sensor of the invention can also have a non-magnetic spacer layer interposed between the free layer and the antiferromagnetic layer or be in contact with the free layer.