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 microwave circulator uses a thin-film exchange-coupled structure to provide an in-plane magnetic field around the circulator. The exchange-coupled structure is a ferromagnetic layer having an in-plane magnetization oriented generally around the circulator and an antiferromagnetic layer exchange-coupled with the ferromagnetic layer that provides an exchange-bias field to the ferromagnetic layer. A plurality of electrically conductive ports are connected to the exchange-coupled structure. Each of the portions or legs of the circulator between the ports may have an electrical coil wrapped around it with each coil connected to an electrical current source. The ferromagnetic resonance (FMR) frequency of the exchange-coupled structure in the absence of an external magnetic field is determined by the properties of the material of ferromagnetic layer and the magnitude of the exchange-bias field due to the exchange-coupling of the ferromagnetic layer to the antiferromagnetic layer.

Abstract: A magnetoresistive sensor having a magnetically stable free layer fabricated from a material having a positive magnetostriction such as a Co—Fe—B alloy. Although the free layer is fabricated from a material that has a positive magnetostriction, which would ordinarily make the free layer unstable, the magnetization of the free layer remains stable because of an induced magnetic anisotropy that has an easy axis of magnetization oriented parallel to the Air-bearing Surface (ABS). This magnetic anisotropy of the free layer is induced by an anisotropic texturing of the surface of the free layer. The resulting anisotropic surface texture is produced by an ion milling process that utilizes an ion beam directed at an acute angle relative to the normal to the surface of the wafer whereon the sensor is fabricated while the wafer is held on a stationary chuck.

Abstract: A microwave circulator uses a thin-film exchange-coupled structure to provide an in-plane magnetic field around the circulator. The exchange-coupled structure is a ferromagnetic layer having an in-plane magnetization oriented generally around the circulator and an antiferromagnetic layer exchange-coupled with the ferromagnetic layer that provides an exchange-bias field to the ferromagnetic layer. A plurality of electrically conductive ports are connected to the exchange-coupled structure. Each of the portions or legs of the circulator between the ports may have an electrical coil wrapped around it with each coil connected to an electrical current source. The ferromagnetic resonance (FMR) frequency of the exchange-coupled structure in the absence of an external magnetic field is determined by the properties of the material of ferromagnetic layer and the magnitude of the exchange-bias field due to the exchange-coupling of the ferromagnetic layer to the antiferromagnetic layer.

Abstract: A magnetoresistive sensor having a pinned layer that includes a first magnetic layer (AP1) a second magnetic layer (AP2) and an antiparallel coupling layer sandwiched between the AP1 and AP2 layers. The AP1 layer is adjacent to a layer of antiferromagnetic material (AFM layer) and is constructed so as to have a long spin diffusion length. The long spin diffusion length of the AP1 layer minimizes the negative GMR contribution of the AP1 layer, thereby increasing the overall GMR effect of the sensor.

Abstract: A magnetoresistive sensor having a hard magnetic pinning layer with an engineered magnetic anisotropy in a direction substantially perpendicular to the medium facing surface. The hard magnetic pinning layer may be constructed of CoPt, CoPtCr, or some other magnetic material and is deposited over an underlayer that has been ion beam etched. The ion beam etch has been performed at an angle with respect to normal in order to induce anisotropic roughness for example in form of oriented ripples or facets oriented along a direction parallel to the medium facing surface. The anisotropic roughness induces a strong uniaxial magnetic anisotropy substantially perpendicular to the medium facing surface in the hard magnetic pinning layer deposited there over.

Abstract: A magnetic field sensing system with a current-perpendicular-to-the-plane (CPP) sensor, like that used for giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR) spin-valve (SV) sensors, operates in a mode different from conventional GMR-SV and TMR-SV systems. An alternating-current (AC) source operates at a fixed selected frequency and directs AC perpendicularly through the layers of the CPP sensor, with the AC amplitude being high enough to deliberately induce a spin-torque in the CPP sensor's free layer. The AC-induced spin-torque at the selected frequency causes oscillations in the magnetization of the free layer that give rise to a DC voltage signal VDC. VDC is a direct result of only the oscillations induced in the free layer. The value of VDC will change in response to the magnitude of the external magnetic field being sensed and as the free layer is driven in and out of resonance with the AC.

Abstract: A current perpendicular to plane dual giant magnetoresistive sensor (dual CPP GMR sensor) that prevents spin torque noise while having high dR/R performance. The sensor has a design that maximizes the GMR effect (dR/R) by providing a pinned layer structure that maximizes the positive GMR contribution of the AP2 layer (or magnetic layer closest to the spacer layer) while minimizing the negative GMR contribution of the AP1 layer. The pinned layer structure includes an AP1 layer that includes a thin CoFe layer that is exchange coupled with an IrMn or IrMnCr AFM layer and has two or more Co layers with a spin blocking layer sandwiched between them. The use of the Co layers and the spin blocking layer in the AP1 layer minimizes the negative contribution of the AP1 layer. The AP2 layer has a plurality of CoFe layers with nano-layers such as Cu sandwiched between the CoFe layers.

Abstract: A tunneling magnetoresistance (TMR) device, like a TMR read head for a magnetic recording hard disk drive, has a magnesium oxide (MgO) tunneling barrier layer and a ferromagnetic underlayer beneath and in direct contact with the MgO tunneling barrier layer. The ferromagnetic underlayer comprises a crystalline material 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 26 and 37. The ferromagnetic underlayer may be the CoxFe(100-x))(100-y)Gey portion of a bilayer of two ferromagnetic layers, for example a CoFe/(CoxFe(100-x))(100-y)Gey bilayer. The specific composition of the ferromagnetic underlayer improves the crystallinity of the MgO tunneling barrier after annealing and improves the tunneling magnetoresistance of the TMR device.

Abstract: EMR elements and methods of fabricating the EMR elements are disclosed. The EMR structure includes one or more layers that form an active region, such as a two-dimensional electron gas (2DEG). The EMR structure has a first side surface, having a plurality of lead protrusions that extend outwardly from the main body of the EMR structure, and an opposing second side surface. The lead protrusions are used to form the current and voltage leads for the EMR element. The active region extends through each lead protrusion and is accessible along a perimeter of each of the lead protrusions. Conductive material is formed along the perimeter of each lead protrusion and contacts the active region of the EMR structure along the perimeter. The lead protrusion and the corresponding conductive material contacting the active region of each lead protrusion form leads for the EMR element, such as current leads and voltage leads.

Abstract: A method of making a current-perpendicular-to-the-plane giant magnetoresistive (CPP-GMR) sensor with a confined-current-path (CCP) layer uses an array of self-assembled ferritin protein molecules with inorganic cores to make the CCP layer in the sensor stack. In one embodiment, the ferritin molecules with cores of insulating oxide particles are deposited on an electrically conductive support layer and the ferritin molecules are dissolved, leaving an array of insulating oxide particles. An electrically conducting layer is deposited over the oxide particles and into the regions between the oxide particles to form the CCP layer. In another embodiment, the ferritin molecules with inorganic particles in their cores are deposited on an electrically insulating support layer and the ferritin molecules are dissolved, leaving an array of inorganic particles that function as an etch mask.

Abstract: Solid-state memories are disclosed that are comprised of cross-point memory arrays. The cross-point memory arrays include a first plurality of electrically conductive lines and a second plurality of electrically conductive lines that cross over the first plurality of electrically conductive lines. The memory arrays also include a plurality of memory cells located between the first and second conductive lines. The memory cells are formed from a metallic material, such as FeRh, having the characteristic of a first order phase transition due to a change in temperature. The first order phase transition causes a corresponding change in resistivity of the metallic material.

Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has an antiparallel free (APF) structure as the free layer and a specific direction for the applied bias or sense current. The (APF) structure has a first free ferromagnetic (FL1), a second free ferromagnetic layer (FL2), and an antiparallel (AP) coupling (APC) layer that couples FL1 and FL2 together antiferromagnetically with the result that FL1 and FL2 have substantially antiparallel magnetization directions and rotate together in the presence of a magnetic field. The thickness of FL1 is preferably greater than the spin-diffusion length of the electrons in the FL1 material. The minimum thickness for FL2 is a thickness resulting in a FL2 magnetic moment equivalent to at least 10 ? Ni80Fe20 and preferably to at least 15 ? Ni80Fe20.

Abstract: A “scissoring-type” current-perpendicular-to-the-plane giant magnetoresistive (CPP-GMR) sensor has magnetically damped free layers. In one embodiment each of the two free layers is in contact with a damping layer that comprises Pt or Pd, or a lanthanoid (an element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Th, Yb, and Lu). Each of the two free layers has one of its surfaces in contact with the sensor's electrically conducting nonmagnetic spacer layer and its other surface in contact with its associated damping layer. A nonmagnetic film may be located between each free layer and its associated damping layer. In another embodiment the damping element is present as a dopant or impurity in each of the two free layers. In another embodiment a nanolayer of the damping element is located within each of the two free layers.

Abstract: A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has a high-resistivity amorphous ferromagnetic alloy in the free layer and/or the pinned layer. The sensor may have an antiparallel (AP)-pinned structure, in which case the AP2 layer may be formed of the high-resistivity amorphous ferromagnetic alloy. The amorphous alloy is an alloy of one or more elements selected from Co, Fe and Ni, and at least one nonmagnetic element X. The additive element or elements is present in an amount that renders the otherwise crystalline alloy amorphous and thus substantially increases the electrical resistivity of the layer. As a result the resistance of the active region of the sensor is increased. The amount of additive element or elements is chosen to be sufficient to render the alloy amorphous but not high enough to substantially reduce the magnetic moment M or bulk electron scattering parameter ?.

Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has an antiparallel free (APF) structure as the free layer and a specific direction for the applied bias or sense current. The (APF) structure has a first free ferromagnetic (FL1), a second free ferromagnetic layer (FL2), and an antiparallel (AP) coupling (APC) layer that couples FL1 and FL2 together antiferromagnetically with the result that FL1 and FL2 have substantially antiparallel magnetization directions and rotate together in the presence of a magnetic field. The thicknesses of FL1 and FL2 are chosen to obtain the desired net free layer magnetic moment/area for the sensor, and the thickness of FL1 is preferably chosen to be greater than the spin-diffusion length of the electrons in the FL1 material to maximize the bulk spin-dependent scattering of electrons and thus maximize the sensor signal.

Abstract: A magnetic head including a CPP GMR read sensor that includes a reference layer, a free magnetic layer and a spacer layer that is disposed between them, where the free magnetic layer and the reference magnetic layer are each comprised of Co2MnX where X is a material selected from the group consisting of Ge, Si, Al, Ga and Sn, and where the spacer layer is comprised of a material selected from the group consisting of Ni3Sn, Ni3Sb, Ni2LiGe, Ni2LiSi, Ni2CuSn, Ni2CuSb, Cu2NiSn, Cu2NiSb, Cu2LiGe and Ag2LiSn. Further embodiments include a dual spin valve sensor where the free magnetic layers and the reference layers are each comprised of Heusler alloys. A further illustrative embodiment includes a laminated magnetic layer structure where the magnetic layers are each comprised of a ferromagnetic Heusler alloy, and where the spacer layers are comprised of a nonmagnetic Heusler alloy.

Abstract: A current perpendicular to plane magnetoresistive sensor having improved resistance amplitude change and reduced spin torque noise. The sensor has an antiparallel coupled pinned layer structure with at least one of the layers of the pinned layer structure includes a high spin polarization material such as Co2FeGe. The sensor can also include an antiparallel coupled free 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 “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.