Abstract: A spin-torque oscillator (STO) has increased magnetic damping of the oscillating free ferromagnetic layer. The Gilbert magnetic damping parameter (?) is at least 0.05, and preferably greater than 0.05. The free layer may be a any type of conventional ferromagnetic material, but contains one or more damping elements as a dopant. The damping element is selected from the group consisting of Pt, Pd and the 15 lanthanide elements. The free layer damping may also be increased by a damping layer adjacent the free layer. One type of damping layer may be an antiferromagnetic material, like a Mn alloy. As a modification to the antiferromagnetic damping layer, a bilayer damping layer may be formed of the antiferromagnetic layer and a nonmagnetic metal electrically conductive separation layer between the free layer and the antiferromagnetic layer. Another type of damping layer may be one formed of one or more of the elements selected from Pt, Pd and the lanthanides.

Abstract: A “thermagnonic” spin-torque oscillator (STO) uses heat flow alone to cause the spin-torque (ST) effect and generate the persistent oscillation of the free layer magnetization. In addition to the conventional free and reference layers, the thermagnonic STO also includes a magnetic oxide layer having a fixed in-plane magnetization, a ferromagnetic metallic layer on one surface of the magnetic oxide layer, a nonmagnetic electrically conductive layer between the free layer and the metallic layer, and an electrically resistive heater on the other surface of the magnetic oxide layer. Due to the thermagnonic effect, heat flow from the magnetic oxide layer through the metallic layer, conductive layer and free layer ultimately results in a spin transfer torque (STT) to the free layer. Electrical sense current flowing in the opposite direction as the heat flow is used to monitor the frequency of oscillation of the free layer magnetization.

Abstract: A “thermagnonic” spin-torque oscillator (STO) uses heat flow alone to cause the spin-torque (ST) effect and generate the persistent oscillation of the free layer magnetization. In addition to the conventional free and reference layers, the thermagnonic STO also includes a magnetic oxide layer having a fixed in-plane magnetization, a ferromagnetic metallic layer on one surface of the magnetic oxide layer, a nonmagnetic electrically conductive layer between the free layer and the metallic layer, and an electrically resistive heater on the other surface of the magnetic oxide layer. Due to the thermagnonic effect, heat flow from the magnetic oxide layer through the metallic layer, conductive layer and free layer ultimately results in a spin transfer torque (STT) to the free layer. Electrical sense current flowing in the opposite direction as the heat flow is used to monitor the frequency of oscillation of the free layer magnetization.

Abstract: A spin-torque oscillator (STO) has increased magnetic damping of the oscillating free ferromagnetic layer. The Gilbert magnetic damping parameter (a) is at least 0.05, and preferably greater than 0.05. The free layer may be a any type of conventional ferromagnetic material, but contains one or more damping elements as a dopant. The damping element is selected from the group consisting of Pt, Pd and the 15 lanthanide elements. The free layer damping may also be increased by a damping layer adjacent the free layer. One type of damping layer may be an antiferromagnetic material, like a Mn alloy. As a modification to the antiferromagnetic damping layer, a bilayer damping layer may be formed of the antiferromagnetic layer and a nonmagnetic metal electrically conductive separation layer between the free layer and the antiferromagnetic layer. Another type of damping layer may be one formed of one or more of the elements selected from Pt, Pd and the lanthanides.

Abstract: A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

Abstract: A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

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: 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: A spin torque oscillation magnetoresistive sensor for measuring a magnetic field. The sensor uses a change in precessional oscillation frequency of a magnetization of a magnetic layer to determine the magnitude of a magnetic field. The sensor can include a magnetic free layer, a magnetic pinned layer and a non-magnetic layer sandwiched therebetween. Circuitry is connected with these layers to induce an electrical current through the layers. Spin polarization of electrons traveling through the device causes a spin torque induced precession of the magnetization of one or more of the layers. The frequency of this oscillation modulates in response to a magnetic field. The modulation of the oscillation frequency can be measured to detect the presence of the magnetic field, and determine its magnitude.

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: A graphene magnetic field sensor has a ferromagnetic biasing layer located beneath and in close proximity to the graphene sense layer. The sensor includes a suitable substrate, the ferromagnetic biasing layer, the graphene sense layer, and an electrically insulating underlayer between the ferromagnetic biasing layer and the graphene sense layer. The underlayer may be a hexagonal boron-nitride (h-BN) layer, and the sensor may include a seed layer to facilitate the growth of the h-BN underlayer. The ferromagnetic biasing layer has perpendicular magnetic anisotropy with its magnetic moment oriented substantially perpendicular to the plane of the layer. The graphene magnetic field sensor based on the extraordinary magnetoresistance (EMR) effect may function as the magnetoresistive read head in a magnetic recording disk drive.

Abstract: A method for manufacturing 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 structure for preventing Electrostatic Discharge (LSD) 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 to 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: 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: A graphene magnetic field sensor has a ferromagnetic biasing layer located beneath and in close proximity to the graphene sense layer. The sensor includes a suitable substrate, the ferromagnetic biasing layer, the graphene sense layer, and an electrically insulating underlayer between the ferromagnetic biasing layer and the graphene sense layer. The underlayer may be a hexagonal boron-nitride (h-BN) layer, and the sensor may include a seed layer to facilitate the growth of the h-BN underlayer. The ferromagnetic biasing layer has perpendicular magnetic anisotropy with its magnetic moment oriented substantially perpendicular to the plane of the layer. The graphene magnetic field sensor based on the extraordinary magnetoresistance (EMR) effect may function as the magnetoresistive read head in a magnetic recording disk drive.

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 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: Approaches for a hard-disk drive suspension interconnect having a wide bandwidth. A suspension interconnect includes a substrate layer, a dielectric layer disposed on the substrate layer, and a plurality of transmission-line (TL) conductors disposed within the dielectric layer. Air gaps may be disposed around the TL conductors to minimize the tendency of the dielectric material to act as an electrical shunt, which impedes high bandwidth signal transmission. An air gap may exist in the dielectric layer between adjacent TL conductors. Additionally, the area adjacent to the plurality of TL conductors, along the direction of signal travel, may alternate between dielectric material and air gaps. Indeed, there need not be any solid material enclosing the TL conductors save for a plurality of dielectric cross ties that provide structural support thereto. The substrate layer may also comprise one or more air gaps underneath a portion of the plurality of TL conductors.

Abstract: An extraordinary magnetoresistive sensor (EMR sensor) having a lead structure that is self aligned with a magnetic shunt structure. To form an EMR sensor according to an embodiment of the invention, a plurality of layers are deposited to form quantum well structure such as a two dimensional electron gas structure (2DEG). A first mask structure is deposited having two openings, and a material removal process is performed to remove portions of the sensor material from areas exposed by the openings. The distance between the two openings in the first mask defines a distance between a set of leads and the shunt structure. A non-magnetic metal is then deposited. A second mask structure is then formed to define shape of the leads.

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.