Abstract: A method for forming a semiconductor memory structure is provided. The method includes following operations. An interlayer is formed over a first ferromagnetic layer, wherein forming the interlayer includes following operations. A first metal film is formed by sputtering a first target material. A first oxygen treatment is conducted to the first metal film to form a first metal oxide film. A second metal oxide film is formed over the first metal oxide film by sputtering a second target material different from the first target material. A second metal film is formed by sputtering a third target material. A second oxygen treatment is conducted to the second metal film to form a third metal oxide film.

Abstract: The present disclosure generally relates to read heads having dual free layer (DFL) sensors. The read head has a sensor disposed between two shields. The sensor is a DFL sensor and has a surface at the media facing surface (MFS). Recessed from the DFL sensor, and from the MFS, is a rear hard bias (RHB) structure. The RHB structure is disposed between the shields as well. In between the DFL sensor and the RHB structure is insulating material. The RHB is disposed on the insulating material. The RHB includes a RHB seed layer as well as a RHB bulk layer. The RHB bulk layer includes a first bulk layer and a second bulk layer, the first bulk layer having a different density relative to the second bulk layer.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a write assist element. Data is written to the disk using the write assist element. A protrusion of the head toward the disk is measured periodically, and an abnormality with the write assist element is detected when a slope of the protrusion measurements indicates the protrusion is increasing.

Abstract: The present disclosure involves electronic test structures, and related methods, for use with one or more magnetoresistive elements at least at the wafer stage of slider manufacturing.

Abstract: According to one embodiment, a magnetic head includes a reading head including first, second, and third reading elements R1, R2, R3 which are arranged in a down track direction with intervals in an air bearing surface. A core width RW2 of the second reading element is half the width of the data track or more, and a core width RW1 of the first reading element and a core width RW3 of the third reading element are less than the core width RW2. The first reading element is opposed to one end of the second reading element and is in a position overlapping a part of an adjacent data track, and the third reading element is opposed to the other end of the second reading element and is in a position overlapping a part of an adjacent data track.

Abstract: A magnetic device may include a magnetic structure, a device structure, and an associated circuit. The magnetic structure may include a patterned layer of material having a predetermined magnetic property. The patterned layer may be configured to, e.g., provide a magnetic field, sense a magnetic field, channel or concentrate magnetic flux, shield a component from a magnetic field, or provide magnetically actuated motion, etc. The device structure may be another structure of the device that is physically connected to or arranged relative to the magnetic structure to, e.g., structurally support, enable operation of, or otherwise incorporate the magnetic structure into the magnetic device, etc. The associated circuit may be electrically connected to the magnetic structure to receive, provide, condition or process of signals of the magnetic device.

Abstract: A data storage device can employ one or more transducing heads that have a data reader and data writer each connected to a substrate of the transducing head. The substrate can be electrified with a predetermined surface charge by a charge circuit of the transducing head to maintain, or alter, a head-media spacing.

Abstract: A method of testing dynamic performances for a slider body of a thermally-assisted magnetic head includes: providing a slider body which is disconnected with a light source unit; removably mounting the slider body to a test head suspension assembly; keeping to provide a flat top beam to the slider body, the flat top beam being aligned with the optical waveguide, and a projection of an incident end of the optical waveguide being located within a light spot of the flat top beam; and testing the dynamic performance of the slider body. It can save the material cost and labor cost, and eliminate a precise optical alignment between an input light and an optical waveguide in the slider body to improve testing efficiency.

Abstract: A method and system provides a near-field transducer (NFT) for a heat assisted magnetic recording (HAMR) transducer. The method and system include forming the disk of the NFT and forming the pin of the NFT. The disk is formed from a first material. The pin is formed from a second material different from the first material. The pin contacts the disk. At least a portion of the pin is between the disk and an air-bearing surface (ABS) location.

Abstract: The presently disclosed technology teaches integrating disc drive electronics into a transducer head. Decreased electrical transit times and data processing times can be achieved by placing the electronics on or within the transducer head because electrical connections may be made physically shorter than in conventional systems. The electronics may include one or more of a control system circuit, a write driver, and/or a data buffer. The control system circuit generates a modified clock signal that has a fixed relation to phase and frequency of a bit-detected reference signal that corresponds to positions of patterned bits on the disc. The write driver writes outgoing data bits received from an external connection to off-head electronics directly to the writer synchronized with the modified clock signal. The data buffer stores and converts digital data bits sent from the off-head electronics to an analog signal that is synchronized with the modified clock signal.

Abstract: A multi reader head has a plurality of readers that are laminated via a gap layer(s), and each of the readers has a structure in which a current-perpendicular-to-plane (CPP) type of magneto-resistive effect element, where a current flows along the lamination direction, is interposed between a pair of shields that function as an electrode, respectively, from both sides in the lamination direction. The shields that are opposed from each other via the gap layer of the readers that are adjacent in the lamination direction by a distance that is not constant, but include a portion with a greater distance between the shields and another portion with a smaller distance between the shields are included. The portion with a greater distance between the shields is situated at a position away from the center on an air bearing surface opposing to a recording medium in the magneto-resistive effect element.

Abstract: A method and apparatus are directed to providing relative movement between a slider configured for heat-assisted magnetic recording and a magnetic recording medium, and causing protrusion of a portion of an air bearing surface (ABS) of the slider in response to activating at least a laser source while maintaining spacing between the protrusion and the medium. A magnitude of at least a portion of the protrusion is measured while maintaining spacing between the protrusion and the medium.

Abstract: A method provides a magnetic transducer having an air-bearing surface (ABS) location. An intermediate layer having a substantially flat bottom surface is provided. A trench is formed in the intermediate layer. The trench is wider in yoke region than in the pole tip region. The trench has a first depth in the yoke region and a second depth less than the first depth in the pole tip region. A portion of the intermediate layer is at the bottom of the trench at the ABS location. A nonmagnetic layer is provided. The nonmagnetic layer fills part of the trench in the pole tip region such that the trench has a third depth less than the second depth at the ABS location. A main pole is provided. The main pole has a leading bevel adjacent to nonmagnetic layer in the portion of the pole tip region of the trench.

Abstract: Near field transducers (NFTs) and devices that include a peg having an air bearing region and an opposing back region, the back region including a sacrificial structure, a disc having a first surface in contact with the peg, and a barrier structure, the barrier structure positioned between the opposing back region of the peg and the first surface of the disc.

Abstract: In accordance with one embodiment, a magnetic head includes a main pole configured to emit a recording magnetic field for affecting a magnetic medium, spin torque oscillator (STO) device in electrical communication with and positioned above the main pole in a track direction, the STO device being configured to generate a high-frequency magnetic field which is superimposed with the recording magnetic field in order to record data to the magnetic medium when current flows to the STO device, and a heat sink positioned near the STO device, the heat sink being configured to reduce a temperature of the STO device when current flows to the STO device. In another embodiment, a method includes forming a heat sink behind a STO device in an element height direction perpendicular to a media facing surface, and/or on both sides of the STO device in a cross-track direction at the media facing surface.

Abstract: In one embodiment, a magnetic head includes a lower shield, a magnetoresistive (MR) film positioned above the lower shield, the MR film including a pinned layer, an intermediate layer positioned above the pinned layer, and a free layer positioned above the intermediate layer, the free layer being configured for sensing data on a magnetic medium, wherein a track width of the MR film is defined by a width of the free layer in a cross-track direction, a bias layer positioned on both sides of the MR film in the cross-track direction, a track insulating film positioned on both sides of the MR film in the cross-track direction and between the MR film and the bias layer, and an upper shield positioned above the bias layer and the MR film, wherein a length of the free layer in an element height direction perpendicular to an air bearing surface of the magnetic head is less than a length of the pinned layer in the element height direction.

Abstract: A thermally assisted magnetic head includes a main magnetic pole layer, a near-field light generating layer having a generating end part generating near-field light arranged within a medium-opposing surface, and an optical waveguide guiding light to the near-field light generating layer. The near-field light generating layer has a laminated structure in which a first thin-film metal layer formed in a thin film form along a direction intersecting the medium-opposing surface and a second thin-film metal layer formed in a thin film form and formed using a second metal larger in hardness than a first metal forming the first thin-film metal layer are alternately laminated. Further, in the second thin-film metal layer, a defect part is formed, the defect part is a part smaller in thickness than another part or is a hole part, and a flat layer part other than the defect part surrounds the defect part.

Abstract: A method of manufacturing a thermally-assisted magnetic recording head includes the steps of: forming a preliminary head section that has a surface to be polished and includes a magnetic pole, a waveguide, and a preliminary plasmon generator; causing a volumetric expansion of the preliminary plasmon generator with heat by introducing light into the core of the waveguide of the preliminary head section; and polishing the surface to be polished of the preliminary head section into a medium facing surface. The preliminary plasmon generator has an end face located in the surface to be polished. In the step of polishing the surface to be polished, the surface to be polished is subjected to polishing with the preliminary plasmon generator expanded in volume, whereby the end face of the preliminary plasmon generator is polished into the front end face, and the preliminary plasmon generator thereby becomes the plasmon generator.

Abstract: According to one embodiment, there is provided a spin torque oscillator including an oscillation layer formed of a magnetic material, a spin injection layer formed of a magnetic material and configured to inject a spin into the oscillation layer, and a current confinement layer including an insulating portion formed of an oxide or a nitride and a conductive portion formed of a nonmagnetic metal and penetrating the insulating portion in a direction of stacking. The conductive portion of the current confinement layer is positioned near a central portion of a plane of a device region including the oscillation layer and the spin injection layer.

Abstract: In one embodiment, a magnetic head includes a magnetoresistive sensor having a free layer and a soft magnetic layer adapted to control a magnetization direction of the free layer and a magnetic domain of the free layer, wherein a close-packed plane of the soft magnetic layer is positioned parallel to an air bearing surface (ABS) of the magnetic head. In another embodiment, a method for forming a magnetic head includes forming a magnetoresistive sensor having a free layer above a substrate and forming a soft magnetic layer adapted to control a magnetization direction of the free layer and a magnetic domain of the free layer, wherein a close-packed plane of the soft magnetic layer is positioned parallel or oblique to an ABS of the magnetic head.

Abstract: A near field transducer with a peg region, an enlarged region disposed adjacent the peg region, and a barrier material disposed between the peg region and the enlarged region. The barrier material reduces or eliminates interdiffusion of material between the peg region and the enlarged region.

Abstract: An apparatus for a heat assisted magnetic recording device that includes a write pole, a near-field transducer, and a heat sink. The near-field transducer is comprised only of a peg disposed adjacent the write pole. The heat sink is disposed between the write pole and at least a portion of the near-field transducer.

Abstract: An apparatus for a heat assisted magnetic recording device that includes a write pole, a near-field transducer, and a heat sink. The near-field transducer is comprised only of a peg disposed adjacent the write pole. The heat sink is disposed between the write pole and at least a portion of the near-field transducer.

Abstract: Methods for preparing an electrode comprise: providing a mixture of carbon particles and a solvent and shearing the mixture to form a dispersion of the carbon particles in the solvent; adding non-fibrillated POLY(TETRAFLUOROETHYLENE) to the dispersion to provide a resultant mixture and shearing the resultant mixture until at least a portion of the poly(tetrafluoroethylene) has been fibrillated; processing the resultant mixture into a sheet; and attaching the sheet onto a current collector. Methods for preparing sheet for the electrode and composition for the sheet are also provided.

Abstract: Implementations disclosed herein allow a magneto-optical polarization rotator to couple light from a light source of a HAMR recording device to waveguide attached to a slider. According to one implementation, the magneto-optical polarization rotator has a magnetophotonic crystal structure with a number of thin film layers configured to rotate the light by 90 degrees.

Abstract: Methods for reducing the surface roughness of magnetic media to be used in storage drives are described. One such method includes forming a recording media on a substrate, the recording media including at least one recording layer configured to store information magnetically, depositing a first layer of carbon on the recording media, the first carbon layer having a first average preselected thickness, etching the first carbon layer to have a second average preselected thickness less than the first average preselected thickness, depositing a second layer of carbon on the etched first carbon layer, the second carbon layer having a third average preselected thickness that is less than the first average preselected thickness, and implanting nitrogen in the second carbon layer.

Abstract: The present invention generally relates to methods for forming a sensor structure utilizing a shallow and narrow hard mask stencil. In one embodiment, a sensor structure is formed by utilizing a four-layered hard mask stencil. The four-layered hard mask stencil includes a first mask layer, a second mask layer disposed over the first hard mask, a third mask layer disposed over the second mask layer, and a forth mask layer disposed over the third mask layer. In another embodiment, a sensor structure is formed by utilizing a three-layered hard mask stencil. The three-layered hard mask stencil includes a first mask layer, a second mask layer disposed over the first mask layer, and a third mask layer disposed over the second mask layer. The sensor structure is formed with a two-step chemical mechanical planarization (CMP) process.

Abstract: A method for manufacturing a disk drive head suspension having a plated load point dimple. An aperture is etched into the spring metal member. A photoresist mask having an opening with load point-defining side walls and a load point diameter is formed over a portion of a spring metal member including the aperture. Metal is plated onto the spring metal member and into the aperture in the opening to form a load point having the load point diameter on the spring metal member.

Abstract: A process sequence for forming a waveguide structure with a light polarization rotator section that converts transverse electric light from a TE light source to transverse magnetic light which is subsequently coupled to a plasmon generator (PG) is disclosed. The light polarization rotator section has a length determined by TE LD light wavelength, and the effective mode index of the two orthogonal fundamental modes, and a slope is formed in one side of the symmetric structure with a 45 degree angle with respect to a bottom surface. Offsets that narrow the cross-track width may be formed on the two sides of the light polarization rotator section to improve symmetry for higher TE to TM polarization conversion efficiency.

Abstract: A method of manufacturing a PMR writer is disclosed that minimizes pole erasure during non-writing and maximize write field during writing by including an AFM-FM phase change material spacer that is in an AFM state during non-writing and switches to a FM state by heating during writing. The main pole layer including the write pole may be formed as a laminated structure by a sputter deposition process wherein a plurality of “n” ferromagnetic layers and “n?1” AFM-FM phase change material layers are laid down in an alternating manner. The AFM-FM phase change material is preferably a FeRh or FeRhX alloy (X=Pt, Pd, or Ir) having a Rh content >35 atomic %, and may also be used as a flux gate to prevent yoke flux from leaking into the write pole tip.

Abstract: A data reader can be configured with at least a magnetically responsive lamination that has a first portion with a first stripe height from an air bearing surface (ABS) and a second portion with a different second stripe height from the ABS. The first portion can be constructed to have a back edge surface shaped at a predetermined angle relative to the ABS by a back edge feature.

Abstract: An HSA transport comb includes an alignment pin extending from the comb body into a tooling hole of the actuator arm, and a separator finger in contact with a suspension assembly of an HGA with the transport comb in a second angular orientation with respect to the actuator arm, but not in a first angular orientation. The transport comb includes a restraining tower extending into a mass-reduction opening of the actuator arm. The restraining tower includes a first lobe that fits within the mass-reduction opening with the transport comb in the first angular orientation, but not with the transport comb in the second angular orientation. The restraining tower also includes a first neck that fits within the mass-reduction opening with the transport comb in either angular orientation, and has a neck height that is greater than the actuator arm thickness.

Abstract: A method of manufacturing a suspension for a disk drive includes providing and assembling an actuator coupling plate, a bend region, a load beam, and a head receiving gimbal. The load beam has a first end and a second end and defines a longitudinal axis that bisects the first end and the second end. The load beam is coupled to the gimbal proximate the first end and includes a base region proximate the second end, the base region having a first lateral section to one side of the longitudinal axis and a second lateral section to another side of the longitudinal axis. The first and the second lateral sections define a gap therebetween, and the base region has a bridge extending across the gap. A constraint layer overlays the gap and the bridge.

Abstract: A magnetic transducer has an air-bearing surface (ABS). The magnetic transducer has a main pole, at least one coil for energizing the main pole and at least one additional pole. The main pole has a yoke and a pole tip having an ABS facing surface. The at least one additional pole is adjacent to the main pole in a down track direction. The additional pole is recessed from the ABS, has a front surface facing the ABS, has at least one side surface, and has at least one flare angle between the front surface and the at least one side surface. The at least one flare angle is measured from the ABS to the at least one side surface and is at least fifty degrees and less than ninety degrees.

Abstract: A method of manufacturing a plasmon generator includes the steps of: an initial film made of a metal polycrystal and including a pre-plasmon-generator portion that later becomes the plasmon generator; heating the initial film with heating light so that a plurality of crystal grains constituting the metal polycrystal grow at least in the pre-plasmon-generator portion; stopping the heating of the initial film; and forming the plasmon generator by processing the initial film after the step of stopping the heating. The step of forming the plasmon generator includes the step of providing the pre-plasmon-generator portion with a front end face that generates near-field light.

Abstract: Aspects of the present invention relate to energy-assisted magnetic recording (EAMR), an EAMR assembly, and methods for fabricating the same. In several embodiments, an EAMR head includes a sub-mount on a slider that has a waveguide configured to receive light from a light source attached to a surface of the sub-mount. The waveguide receives the light at a top surface of the slider and routes the light to be near an air bearing surface (ABS) of the slider where energy of the light can be used to heat up a spot on a recording media disk that is proximate the ABS. The waveguide also routes a portion of the light back to the top surface of the slider where the light exits the waveguide and is detected by a light detector located along the surface of the sub-mount.

Abstract: A magnetic write head having a write pole with a novel configuration improving write field strength and field gradient while also reducing adjacent track interference and far track interference. The write pole is configured with a pole tip portion that has a narrow track width, preferably 15-30 degrees and a main yoke portion with a larger flare angle of about 45 degrees. The write pole also has an intermediate portion located between the pole tip and main pole portions. The intermediate portion includes a first portion adjacent to the pole tip that has a flare angle greater than the flare angle of the main yoke and has a second portion with a flare angle less than the flare angle of the yoke.

Abstract: Various embodiments may position a side shield adjacent to and separated from a stack sidewall of a magnetic stack with the side shield having a shield layer disposed between the stack sidewall and a permanent magnet. The permanent magnet can be separated from a first portion of the shield layer by a diffusion barrier that decouples the permanent magnet from the shield layer.

Abstract: A magnetic write head is disclosed that includes a slider that includes a laser diode having a light-emitting edge or surface of a laser diode and an optical waveguide. The disclosed magnetic write head also includes a dielectric layer disposed in a gap between the laser diode and an input to the optical waveguide. The dielectric layer fills the gap completely and provides a low-loss optical pathway for the laser diode to the input of the optical waveguide. Also disclosed is a method that includes spinning on a dielectric in a gap between the light-emitting surface and the optical waveguide coupler, wherein after the spinning on, the laser diode is optically coupled to the optical waveguide coupler through the dielectric.

Abstract: A plasmon generator of a thermally-assisted magnetic recording head has a first configuration member having a near-field light generation end surface at an ABS, and a second configuration member being in contact with main magnetic pole, and terminating at a front end portion of a slope positioned at the position recessed from the ABS. An end part of a separator layer, which is interposed between the main magnetic pole and the first configuration member, on a side opposite to the ABS is at a position more recessed from the air bearing surface than the front end portion of the slope of the second configuration member.

Abstract: A TAMR (Thermal Assisted Magnetic Recording) write head uses the energy of optical-laser excited surface plasmons in a plasmon generator to locally heat a magnetic recording medium and reduce its coercivity and magnetic anisotropy. The optical radiation is transmitted to the plasmon generator by means of a waveguide, whose optical axis (centerline) is tilted relative to either or both the backside surface normal and ABS surface normal in order to eliminate back reflections of the optical radiation that can adversely affect the properties and performance of the laser. Variations of the disclosure include tilting the plasmon generator, the waveguide and the laser diode.

Abstract: A write portion for a thermally assisted magnetic head slider includes an air bearing surface facing to a magnetic recording medium; a write element having an opposed-to-magnetic recording medium surface; a waveguide for guiding light generated by a light source module mounted on a substrate of the thermally assisted magnetic head slider; and a plasmon unit provided around the write element, which has a near-field light generating surface for propagating near-field light to the air bearing surface. And only the opposed-to-magnetic recording medium surface of the write element is covered by a carbon layer. The invention can prevent corrosive elements in the write portion from being corroded and prevent the write element from being worn and abraded not only, and maintain stable thermal ability for a plasmon unit but also.

Abstract: A method for manufacturing a magnetic write pole of a magnetic write head that achieves improved write pole definition reduced manufacturing cost and improves ease of photoresist mask re-work. The method includes the use of a novel bi-layer hard mask beneath a photoresist mask. The bi-layer mask includes a layer of silicon dielectric, and a layer of carbon over the layer of silicon dielectric. The carbon layer acts as an anti-reflective coating layer that is unaffected by the photolithographic patterning process used to pattern the write pole and also acts as an adhesion layer for resist patterning. In the event that the photoresist patterning is not within specs and a mask re-work must be performed, the bi-layer mask can remain intact and need not be removed and re-deposited. In addition, the low cost and ease of use silicon dielectric and carbon reduce manufacturing cost and increase throughput.

Abstract: A write pole can have a magnetically conductive pole tip has at least one corner. The at least one corner may be chamfered to limit magnetic saturation of the conductive pole tip. The conductive pole tip can have one or more beveled surface that has a chamfered corner which extends a predetermined distance along an edge of the write pole.

Abstract: A method for bonding a first substrate to a second substrate is described. The first substrate includes a first plurality of solder pads, a first alignment mark set, and a first plurality of dots. The second substrate includes a second plurality of solder pads, a second alignment mark set, and a second plurality of dots configured to interlock with the first plurality of dots. The method includes aligning the first alignment mark set with the second alignment mark set. The first alignment mark sets being aligned corresponds to the dots and the solder pads being aligned. The method also includes locking the first plurality of dots with the second plurality of dots to form an interlocking key. The method also includes reflowing at least one of the first and second pluralities of solder pads. The dots remain substantially solid during the reflow.

Abstract: In one embodiment, a magnetic head includes a main pole adapted for producing a writing magnetic field, a trailing shield positioned on a trailing side of the main pole, wherein a trailing gap is positioned between the trailing shield and the main pole, and a side shield positioned on at least one side of the main pole in a cross-track direction, wherein a side gap is positioned between the side shield and the main pole, wherein the main pole has an asymmetrical shape at an air bearing surface (ABS) thereof. In another embodiment, a method may be employed for forming a magnetic head having a main pole that has an asymmetrical shape at an ABS thereof.

Abstract: A method for manufacturing a read head includes the step of depositing a conductive filler into a plurality of holes that extend through a wafer. Each of the holes extends from a wafer top surface to a wafer bottom surface. Each of the holes includes an inner surface that includes an insulative layer. The method further includes the steps of fabricating a read transducer on the wafer top surface, and depositing a plurality of electrically conductive leading connection pads on the wafer bottom surface. The plurality of electrically conductive leading connection pads are in electrical contact with the conductive filler.

Abstract: A method fabricates a magnetic transducer having a nonmagnetic layer and an ABS location corresponding to an ABS. Etch stop and nonmagnetic etchable layers are provided. A side shield layer is provided between the ABS location and the etch stop and etchable layers. A pole trench is formed in the side shield and etchable layers. The pole trench has a pole tip region in the side shield layer and a yoke region in the etchable layer. A nonmagnetic side gap layer, at least part of which is in the pole trench, is provided. A remaining portion of the pole trench has a location and profile for a pole and in which at least part of the pole is formed. A write gap and trailing shield are provided. At least part of the write gap is on the pole. At least part of the trailing shield is on the write gap.

Abstract: A method of reclaiming a head suspension includes detaching a slider 225 from a tongue 221 of the head suspension and removing an adhesive 227 remaining on the tongue 221. Removing the adhesive 227 remaining on the tongue 221 includes feeding a solvent 243, which promotes the removal of the adhesive 227, to a part of the tongue 221 where the adhesive 227 remains and promoting the removal of the remaining adhesive 227 from the tongue 221 by applying physical energy to the adhesive remaining part on the tongue 221. The physical energy is produced by heating, supersonic vibration, and the like. The method easily removes the adhesive 227 from the tongue 221 without directly applying mechanical force to the tongue 221, thereby improving yields.

Abstract: Embodiments described herein generally relate to connecting Electronic Lapping Guides (ELG) to a lapping controller such that the number of wire bonds from the controller to a row of read heads is minimized. When lapping the air bearing surface of the read heads, the electrical resistances of the ELGs are monitored to adjust the lapping process and set the stripe height for read sensors in the read heads. Once the resistance corresponds to the desired stripe height, the lapping process is stopped. To measure the resistance, each ELG may be electrically coupled to the same substrate—i.e., share the same common ground. The lapping controller applies a voltage potential across the ELGs using a wire bonded to a pad in the respective read head and one or more connections to the grounded substrate. This configuration avoids having to bond two wires onto each read head.