Abstract: A “scissoring-type” current-perpendicular-to-the-plane (CPP) magnetoresistive sensor with dual ferromagnetic sensing or free layers separated by a nonmagnetic spacer layer has improved stability as a result of etch-induced uniaxial magnetic anisotropy in each of the free layers. Each of the two ferromagnetic free layers has an etch-induced uniaxial magnetic anisotropy and an in-plane magnetic moment substantially parallel to its uniaxial anisotropy in the quiescent state, i.e., the absence of an applied magnetic field. The etch-induced uniaxial anisotropy of each of the free layers is achieved either by direct ion etching of each of the free layers, and/or by ion etching of the layer on which each of the free layers is deposited. A strong magnetic anisotropy is induced in the free layers by the etching, which favors generally orthogonal orientation of the two free layers in the quiescent state.

Abstract: A magnetoresistive (MR) read head based on the spin accumulation effect has no electrical terminal and associated insulating layer in the read gap. The spin-accumulation type MR read head has an electrically conductive strip located on an insulating layer on the lower magnetic shield with a first end at the sensing end of the head and a second end at the back end of the head recessed from the sensing end. At the sensing end of the head, the upper magnetic shield is located on the free layer without an insulating layer. A resistance-detection circuit is electrically coupled to the upper shield and the lower shield at the back end of the head. At the back end of the head, an electrical terminal is located on the fixed layer and electrically insulated from the upper shield and a current-supply circuit is electrically coupled to the terminal and the lower shield.

Abstract: A current-perpendicular-to-the-plane (CPP) spin-valve (SV) magnetoresistive sensor uses an antiparallel (AP) pinned structure and has a ferromagnetic alloy comprising Co, Fe and Si in the reference layer of the AP-pinned structure and optionally in the CPP-SV sensor's free layer. The reference layer or AP2 layer is a multilayer of a first AP2-1 sublayer that contains no Si and is in contact with the AP-pinned structure's antiparallel coupling (APC) layer, and a second AP2-2 sublayer that contains Si and is in contact with the CPP-SV sensor's spacer layer. The Si-containing alloy may consist essentially of only Co, Fe and Si according to the formula (CoxFe(100-X))(100-y)Siy where the subscripts represent atomic percent, x is between about 45 and 55, and y is between about 20 and 30.

Abstract: A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has a ferromagnetic alloy comprising Co, Fe and Ge in the sensor's free layer and/or pinned layer. The sensor may be a simple pinned structure, in which case the pinned layer may be formed of the CoFeGe ferromagnetic alloy. Alternatively, the sensor may have an AP-pinned layer structure, in which case the AP2 layer may be formed of the CoFeGe ferromagnetic alloy. The Ge-containing alloy comprises Co, Fe and Ge, wherein Ge is present in the alloy in an amount between about 20 and 40 atomic percent, and wherein the ratio of Co to Fe in the alloy is between about 0.8 and 1.2. More particularly, the CoFeGe alloy may consist essentially of only Co, Fe and Ge according to the formula (CoxFe(100-x))(100-y)Gey where the subscripts represent atomic percent, x is between about 45 and 55, and y is between about 23 and 37.

Abstract: A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has an improved antiparallel (AP) pinned structure, i.e., a structure with first (AP1) and second (AP2) ferromagnetic layers separated by a nonmagnetic antiparallel coupling (APC) layer with the magnetization directions of AP1 and AP2 oriented substantially antiparallel. The AP2 ferromagnetic layer (the layer in contact with the SV spacer layer) is an alloy of a ferromagnetic material and one or more additive elements of Cu, Au and Ag. The additive elements reduce the magnetic moment of the AP2 layer, which enables its thickness to be increased so that its magnetic moment remains close to the magnetic moment of the AP1 ferromagnetic layer. The thicker AP2 layer allows for more bulk spin-dependent scattering of electrons which increases the magnetoresistance of the sensor.

Abstract: Magnetoresistive (MR) read elements and associated methods of fabrication are disclosed. A free layer and/or a pinned layer of an MR read element are formed from a magnetic material such as Co2?x?yMn1+xAl1+y, Co2?x?yMn1+xSi1+y, Co2?x?yMn1+xGe1+y, and Co2?x?yFe1+xSi1+y, where x and y are selected to create an off-stoichiometric alloy having a crystalline structure that is chemically disordered. The chemically disordered magnetic material has a lower spin-polarization than a Heusler alloy, but still exhibits acceptable GMR amplitudes and low spin-torque noise.

Abstract: An antiferromagnetically exchange-coupled structure for use in a magnetic device, such as a magnetoresistive sensor, includes an enhancement layer formed of a chemically-ordered tetragonal-crystalline alloy, a chemically-ordered tetragonal-crystalline Mn-alloy antiferromagnetic layer in contact with the enhancement layer, and a ferromagnetic layer exchange-coupled with the antiferromagnetic layer. The enhancement layer is an alloy selected from the group consisting of alloys of AuCu, FePt, FePd, AgTi3, Pt Zn, PdZn, IrV, CoPt and PdCd, and the antiferromagnetic layer is an alloy of Mn with Pt, Ni, Ir, Pd or Rh. The enhancement layer enhances the transformation of the Mn alloy from the chemically-disordered phase to the chemically-ordered phase.

Abstract: A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has an insulating layer with at least one aperture that confines the flow of sense current through the active region. The apertures are located closer to the sensing edge of the sensor than to the back edge of the sensor. The aperture (or apertures) are patterned by e-beam lithography, which enables the number, size and location of the apertures to be precisely controlled. The insulating layer may be located inside the electrically conductive nonmagnetic spacer layer, or outside of the magnetically active layers of the spin-valve. More than one insulating layer may be included in the stack to define conductive current paths where the apertures of the insulating layers overlap. The apertures are filled with electrically conductive material, typically the same material as that used for the spacer layer.

Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive (MR) sensor has an improved free layer structure that includes a first ferromagnetic interface layer on the sensor's nonmagnetic spacer layer, a first electrically conductive interlayer on the first interface layer, a central ferromagnetic NiFe alloy free layer on the first interlayer, a second electrically conductive interlayer on the central free layer, and a second ferromagnetic interface layer on the second interlayer. The first ferromagnetic interface layer, central ferromagnetic free layer, and second ferromagnetic interface layer are ferromagnetically coupled together across the electrically conductive interlayers so their magnetization directions remain parallel. The free layer structure may be used in single or dual CPP sensors and in spin-valve or tunneling MR sensors.

Abstract: A dual current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has a free ferromagnetic layer formed of a Heusler alloy and each of the pinned ferromagnetic layers formed of a ferromagnetic material other than a Heusler alloy, like a conventional CoFe or NiFe material. The Heusler alloy material in the free layer may be a known Heusler alloy material or an alloy with a composition substantially the same as that of a known Heusler alloy, and which results in high magnetoresistance due to enhanced spin polarization and/or enhanced spin-dependent scattering compared to conventional ferromagnetic materials. Each of the two pinned ferromagnetic layers may be an antiparallel (AP) pinned structure wherein first (AP1) and second (AP2) ferromagnetic layers are separated by a nonmagnetic antiparallel coupling (APC) layer with the magnetization directions AP1 and AP2 layers oriented substantially antiparallel.

Abstract: An antiferromagnetically exchange-coupled structure for use in a magnetic device, such as a magnetoresistive sensor, includes an underlayer formed of a chemically-ordered tetragonal-crystalline alloy, a chemically-ordered tetragonal-crystalline Mn-alloy antiferromagnetic layer in contact with the underlayer, and a ferromagnetic layer exchange-coupled with the antiferromagnetic layer. The underlayer is an alloy selected from the group consisting of alloys of AuCu, FePt, FePd, AgTi3, Pt Zn, PdZn, IrV, CoPt and PdCd, and the antiferromagnetic layer is an alloy of Mn with Pt, Ni, Ir, Pd or Rh. The underlayer enhances the transformation of the Mn alloy from the chemically-disordered phase to the chemically-ordered phase.

Abstract: A magnetoresistive sensor based on the spin accumulation effect has an in-stack biasing structure with a ferromagnetic biasing layer that is magnetically-coupled orthogonally with the sensor free ferromagnetic layer across a spacer layer. The sensor has an electrically conductive strip with a first tunnel barrier and a free ferromagnetic layer on the front or sensing end of the strip and second tunnel barrier and a fixed ferromagnetic layer on the back end of the strip. A magnetically-coupling spacer layer is formed on the free layer and the ferromagnetic biasing layer is formed on the spacer layer. The magnetically-coupling layer induces direct orthogonal magnetic coupling between the in-plane magnetization directions of the biasing layer and the free layer.

Abstract: A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has an improved antiparallel (AP) pinned structure. The AP-pinned structure has two ferromagnetic layers separated by a nonmagnetic antiparallel coupling (APC) layer and with their magnetization directions oriented antiparallel. One of the ferromagnetic layers in the AP-pinned structure is the reference layer in contact with the CPP-SV sensor's nonmagnetic electrically conducting spacer layer. In the improved AP-pinned structure each of the ferromagnetic layers has a thickness greater than 30 ?, preferably greater than approximately 50 ?, and the APC layer is either Ru or Ir with a thickness less than 7 ?, preferably about 5 ? or less. The ultrathin APC layer, especially if formed of iridium (Ir), provides significant coupling strength to allow the thick ferromagnetic layers to retain their magnetization directions in a stable antiparallel orientation.

Abstract: A magnetically-coupled structure has two ferromagnetic layers with their in-plane magnetization directions coupled orthogonally across an electrically-conducting spacer layer that induces the direct orthogonal magnetic coupling. The structure has application for in-stack biasing in a current-perpendicular-to-the-plane (CPP) magnetoresistive sensor. One of the ferromagnetic layers of the structure is a biasing ferromagnetic layer and the other ferromagnetic layer is the sensor free layer. An antiferromagnetic layer exchange-couples the biasing layer to fix its moment parallel to the moment of the sensor pinned layer. This allows a single annealing step to be used to set the magnetization direction of the biasing and pinned layers. The electrically-conducting spacer layer, the biasing layer and the antiferromagnetic layer that exchange-couples the biasing layer may all extend beyond the edges of the sensor stack.

Abstract: An extraordinary magnetoresistance (EMR) sensor uses a ferromagnetic multilayer to provide perpendicular magnetic biasing for the sensor. The ferromagnetic multilayer has intrinsic perpendicular magnetic anisotropy and is preferably on top of the EMR active film. The multilayer comprises alternating films of Co, Fe or CoFe and Pt, Pd or PtPd with the preferred multilayer being alternating Co/Pt or Co/Pd films. A diffusion barrier may be located between the EMR active film and the ferromagnetic multilayer.

Abstract: An extraordinary magnetoresistance (EMR) sensor has an antiferromagnetic/ferromagnetic exchange-coupled bilayer structure on top of the EMR active film. The ferromagnetic layer in the bilayer structure has perpendicular magnetic anisotropy and is exchange-biased by the antiferromagnetic layer. The antiferromagnetic/ferromagnetic bilayer structure provides a magnetic field perpendicular to the plane of the EMR active film to bias the magnetoresistance vs. field response of the EMR sensor. The ferromagnetic layer may be formed of any of the ferromagnetic materials useful for perpendicular magnetic recording, and is prepared in a way that its anisotropy axis is significantly out-of-plane. The antiferromagnetic layer is formed of any of the known Mn alloys, such as PtMn, NiMn, FeMn, IrMn, PdMn, PtPdMn and RhMn, or any of the insulating antiferromagnetic materials, such as those based on the cobalt oxide and nickel oxide antiferromagnetic materials.

Abstract: A magnetically-coupled structure has two ferromagnetic layers with their in-plane magnetization directions coupled orthogonally across an electrically-conducting spacer layer that induces the direct orthogonal magnetic coupling. The structure has application for in-stack biasing in a current-perpendicular-to-the-plane (CPP) magnetoresistive sensor. One of the ferromagnetic layers of the structure is an antiparallel-pinned biasing layer and the other ferromagnetic layer is the sensor free layer. The antiparallel-pinned biasing layer has first and second ferromagnetic films separated by an antiferromagnetically-coupling film. An antiferromagnetic layer exchange-couples the first ferromagnetic film of the biasing layer to fix the net moment of the biasing layer parallel to the moment of the sensor pinned layer. This allows a single annealing step to be used to set the magnetization direction of the biasing and pinned layers.

Abstract: A magnetoresistive device of the type with a pinned ferromagnetic layer and a free ferromagnetic layer separated by a nonmagnetic spacer layer has an exchange-coupled antiferromagnetic/ferromagnetic structure that uses a half-metallic ferromagnetic Heusler alloy with its near 100% spin polarization as the pinned ferromagnetic layer. The exchange-coupled structure includes an intermediate ferromagnetic layer between the AF layer and the pinned half-metallic ferromagnetic Heusler alloy layer, which results in exchange biasing. Magnetoresistive devices that can incorporate the exchange-coupled structure include current-in-the-plane (CIP) read heads and current-perpendicular-to-the-plane (CPP) magnetic tunnel junctions and read heads. The exchange-coupled structure may be located either below or above the nonmagnetic spacer layer in the magnetoresistive device.

Abstract: A dual-layer type perpendicular magnetic recording disk for use in a perpendicular magnetic recording system that uses a single pole recording head has a laminated underlayer that has at least two ferromagnetic films exchange-coupled across an antiferromagnetic coupling layer. The magnetic moments of the ferromagnetic layers in the laminated underlayer are oriented antiparallel. The laminated underlayer provides a soft magnetically permeable flux return path without undesirable domain walls and associated media noise, with controllable permeability and minimization of saturation of the upper ferromagnetic layers. In one embodiment the moments of the ferromagnetic layers in the underlayer are oriented generally radially on the disk. In another embodiment the moments are oriented generally circumferentially in the track direction on the disk, so that the beneficial effect of the soft magnetic underlayer occurs primarily only during the writing process.

Abstract: A magnetoresistive device of the type with a pinned ferromagnetic layer and a free ferromagnetic layer separated by a nonmagnetic spacer layer has an exchange-coupled antiferromagnetic/ferromagnetic structure that uses a half-metallic ferromagnetic Heusler alloy with its near 100% spin polarization as the pinned ferromagnetic layer. The exchange-coupled structure includes an intermediate ferromagnetic layer between the AF layer and the pinned half-metallic ferromagnetic Heusler alloy layer, which results in exchange biasing. Magnetoresistive devices that can incorporate the exchange-coupled structure include current-in-the-plane (CIP) read heads and current-perpendicular-to-the-plane (CPP) magnetic tunnel junctions and read heads. The exchange-coupled structure may be located either below or above the nonmagnetic spacer layer in the magnetoresistive device.