Abstract: According to one embodiment, a magnetic head includes a reproducing section. The reproducing section detects a medium magnetic field recorded in a magnetic recording medium. The reproducing section includes a stacked film and a magnetic field application unit. The stacked film includes a first magnetization layer and a second magnetization layer. The first magnetization layer has a perpendicular magnetic anisotropy. A magnetization of the first magnetization layer being is fixed. The second magnetization layer is stacked with the first magnetization layer and oscillates. The magnetic field application unit is stacked with the stacked film and applies a bias magnetic field having a component along the first axis to the stacked film. A resistance of the stacked film changes in accordance with the medium magnetic field when a current not less than a value at which the second magnetization layer oscillates is passed.

Abstract: A perpendicular magnetic recording (PMR) head is fabricated with main pole and a trailing edge shield antiferromagnetically coupled across a write gap by either having the write gap layer formed as a synthetic antiferromagnetic tri-layer (SAF) or formed as a monolithic layer of antiferromagnetic material. The coupling improves the write performance of the writer by enhancing the perpendicular component of the write field and its gradient. Methods of fabricating the writer are provided.

Abstract: A thin-film magnetic head has a high write performance because its shape is smooth without roughness. The thin-film magnetic head includes a slider substrate, a write element and an antireflection film. The slider substrate has an air bearing surface at one side and supports a first support layer. The first support layer has a leading shield, and the leading shield has a low-level flat part, a slope part and a high-level flat part continuously arranged at one side in the recited order toward the air bearing surface. The antireflection film entirely covers the low-level flat part, the slope part and the high-level flat part of the leading shield. The write element has a recording magnetic pole film, and the recording magnetic pole film is formed above the antireflection film.

Abstract: A magnetic recording head includes a main magnetic pole generating a recording magnetic field, a trailing shield, a recording coil generating a magnetic field and a high frequency oscillator. The trailing shield includes a magnetic region including a gap side end surface facing a write gap and a nonmagnetic film arranged in the vicinity of the write gap in the trailing shield, and within a plane including track width direction centers of the main magnetic pole and the high frequency oscillator and being perpendicular to a recording layer of a recording medium, a film thickness of the nonmagnetic film along a track moving direction is substantially equivalent to or more than a half of a distance from the gap side end surface to the nonmagnetic film.

Abstract: A perpendicular magnetic write head includes: a magnetic pole having an end face on an air bearing surface; and side shield layers each having an end face on the air bearing surface, and arranged on both sides, in a write track width direction, of the magnetic pole with a side gap in between. The end face of the magnetic pole has a geometry in which a width at a trailing edge is larger than a width at a leading edge. Relationship D1<D2, D1<D3, and D3?D2 are satisfied in the air bearing surface, where D1 is a gap length of the side gap at the trailing edge, D2 is a gap length of the side gap at the leading edge, and D3 is a gap length of the side gap at any position between the trailing edge and the leading edge.

Abstract: A recording head including a first electrode, a first magnetic layer, a second magnetic layer, a first intermediate layer, a third magnetic layer, a second electrode, and a magnetic pole. A product of saturated magnetization of the first magnetic layer and a lateral area of the first magnetic layer is larger than a product of saturated magnetization of the third magnetic layer and a lateral area of the third magnetic layer.

Abstract: A magnetic write head having a trailing shield configured to optimize both write field strength and field gradient. The write head includes a write pole, a trailing gap layer formed over the trailing edge of the write pole and a trailing magnetic shield formed over the non-magnetic write gap layer such that the non-magnetic write gap layer is sandwiched between the trailing magnetic shield and the write pole. The trailing magnetic shield has a first surface disposed at the air bearing surface and second surface disposed away from the air bearing surface that is tapered at an angle of 20 to 75 degrees relative to the trailing edge of the write pole.

Abstract: A magnetic recording head includes a magnetic pole, a spin torque oscillator, a first shield and a second shield. The magnetic pole has an air-bearing surface. The spin torque oscillator is provided so that a first side of the spin torque oscillator faces the magnetic pole in a first direction parallel to the air-bearing surface. The first shield includes a granular magnetic material, and is provided so that two portions of the first shield sandwich the spin torque oscillator in a second direction which is parallel to the air-bearing surface and perpendicular to the first direction. The second shield is provided on a second side of the spin torque oscillator opposite to the first side.

Abstract: A magnetic write head for magnetic data recording that incorporates a novel magnetic oscillation generator stricture that sets up a magnetic oscillation in the magnetic media for improving writing and that also narrows the write width and reduces adjacent track interference by suppressing writing in regions outside of the desired data track. The magnetic oscillation generating structure includes a centrally disposed magnetic assist element that generates an oscillating magnetic field that oscillates in a direction that will assist the write pole in writing to the magnetic medium. The magnetic oscillation generating structure also includes first and second magnetic non-assist elements at either side of the assist element. The non-assist elements generate a magnetic field that oscillates in a second direction that is opposite to the first direction, which counteracts the magnetic write assist from the centrally disposed magnetic assist element and acts to suppress writing in these side regions.

Abstract: The invention discloses a MAMR head that has the STO stack placed at the trailing side of the write element, with both STO and write element completely self-aligned in the cross track direction. A method for defining both the MP and the STO stack geometries in a single step is also described.

Abstract: An example magnetic writing head includes a main magnetic pole, a coil to generate an ampere magnetic field to magnetize the main magnetic pole to cause the magnetized main magnetic pole to generate a magnetic field, and a laminated body. The laminated body includes a first magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole and a second magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole.

Abstract: In one embodiment, a magnetic data storage system includes a main pole power supply adapted for supplying an excitation current to a main pole coil, a microwave-assisted magnetic recording (MAMR) device including a spin-torque oscillator (STO) element, the STO element having a field generation layer (FGL) and a polarization layer, a timing-control circuit adapted for determining a duration of a main pole magnetic moment inversion process and signaling a start of the main pole magnetic moment inversion process, and a current-regulating circuit comprising an STO power supply adapted for supplying current to the STO element, wherein the STO power supply prevents degradation of a single rotating magnetic domain structure in the FGL into a closure magnetic domain structure in the FGL. Other systems and methods for preventing degradation of the single rotating magnetic domain structure in the FGL into a closure magnetic domain structure are described for more embodiments.

Abstract: A perpendicular magnetic recording (PMR) head is fabricated with a configuration of leading edge shields and trailing edge shields that reduce the leakage of flux between the main pole and the shields. The reduction of leakage is achieved by eliminating the sharp 90° corner between the backside surfaces of the shields and the surfaces adjacent to the main pole. In one embodiment the corner is replaced by two successive acute angles, in another embodiment it is replaced by a rounded surface. In a final embodiment, leakage between the pole and trailing edge shield is achieved by shortening the length of the write gap by forming the shield with a double taper.

Abstract: According to one embodiment, a perpendicular magnetic recording head includes a main magnetic pole having a trailing side and two lateral sides, a magnetic shield near the trailing side and both lateral sides of the main magnetic pole, the magnetic shield comprising: a first soft magnetic film with a relatively high saturation flux density positioned facing depthwise from a floating surface side thereof, a second soft magnetic film with a relatively low saturation flux density, and a first non-magnetic film. The head also includes a non-magnetic film interposed between the magnetic shield and the main magnetic pole, a first magnetic film magnetically coupled to the magnetic shield and the main magnetic pole on a side opposite a floating surface side thereof, and a coil surrounding a magnetic circuit, the magnetic circuit comprising the main magnetic pole and the first magnetic film. Other systems and methods are also described.

Abstract: A PMR writer is disclosed that includes at least one of a recessed center section in the write pole trailing edge and a center recessed trailing shield to improve the field gradient at track edge. In all embodiments, there is a non-uniform write gap between the trailing edge and the trailing shield. The recessed portion of the write pole trailing edge and/or center recess of the trailing shield has a thickness from 10 to 40 nm in a down-track direction and a width in a cross-track direction of 20 to 200 nm. The distance between the center recess and a corner of the trailing edge is from 20 to 80 nm. A sequence of steps is provided to fabricate the two embodiments of the present invention.

Abstract: A perpendicular magnetic write head having improved Bit Error Rate (BER), Adjacent Track Interference (ATI) and Far Track Interference (FTI). The write head includes a write pole and a trailing wrap-around magnetic shield. A permanent magnetic is located at either outer side of the shield. These magnets are magnetized to have magnetizations that are oriented in the same direction, in a direction that is perpendicular to the track direction and parallel with the air bearing surface.

Abstract: A write head, the write head having an air bearing surface, the write head including a magnetic write pole, wherein at the air bearing surface, the write pole has a trailing surface, a leading surface that is opposite the trailing surface, and first and second surfaces; a trailing shield proximate the trailing surface of the magnetic write pole; first and second gaps proximate the first and second surfaces of the magnetic write pole; first and second side shields proximate the first and second gaps, each of the first and second side shields having a trailing shield surface; and first and second antiferromagnetic-coupling layers positioned between the trailing shield surfaces of the first and second side shields and the trailing shield.

Abstract: In high frequency magnetic assisted recording technique, a spin torque oscillator that stably oscillates at a low current and a magnetic recording head with high recording density are provided. In a magnetic recording head including an oscillator that generates a high frequency magnetic field, a spin injection layer structure of two laminated magnetic layers which are coupled to be anti-parallel is adopted. A product Ms×t of the saturated magnetization Ms and the film thickness t of the first magnetic layer close to a field generation layer is smaller than a product Ms×t of the second magnetic layer remote from the field generation layer.

Abstract: Minute elements are formed while a photo deviation is suppressed between a spin torque oscillator and a main pole and damage is prevented on the ends of the spin torque oscillator in microwave-assisted recording. A magnetic recording head used for microwave-assisted recording includes: a main pole; a spin torque oscillator that is disposed on the main pole and includes a magnetization high-speed rotation layer for rotating magnetization at a high speed by a spin torque; a protective film that is disposed in the track width direction of the spin torque oscillator; an insulating film formed over the wall surfaces of the main pole and the wall surfaces of the protective film; and a magnetic film formed on the insulating film so as to cover at least the main pole.

Abstract: A magnetic head having a magnetic wiggler structure for initiating a high frequency magnetic oscillation in a magnetic to improve media-writeability and increase data density. The wiggler structure includes a plurality of magnetic layers that are antiparallel coupled with one another across non-magnetic antiparallel coupling layers. The wiggler structure is arranged just up-track from the point of data writing so that the high frequency oscillation is initiated just prior to the writing of data on the magnetic media.

Abstract: A magnetic write pole structure that is configured to greatly simplify the manufacture of a perpendicular magnetic write head. The write head has a magnetic yoke that is oriented along a plane that is perpendicular to the direction of the data track. This allows the entire yoke to be formed in a single electroplating step, rather than being built up in several plated layers. The yoke can also be formed with magnetic side shields, or with a trailing or wrap around shield, which can be integral with the rest of the yoke and can be advantageously formed in the same, single electroplating step.

Abstract: A thin-film magnetic head is constructed such that a main magnetic pole layer, a write shield layer, a gap layer, and a thin-film coil are laminated on a substrate. The write shield layer has an opposing shield part opposing the main magnetic pole layer and a front shield part. The front shield part is connected to the opposing shield part without straddling the thin-film coil. Besides, the front shield part has a shield front end face disposed in the medium-opposing surface and a shield upper end face formed distanced from the medium-opposing surface. Further, the front shield part has a shield connecting part. The shield front end face is connected to the shield upper end face by the shield connecting part.

Abstract: A write head for use in a magnetic disk drive and methods of manufacturing the same. When a non-magnetic reactive ion etching (RIE) stop layer is used in a damascene main pole fabrication process, the leading edge shield and the side shield have a magnetic separation. By replacing a non-magnetic RIE stop layer with a magnetic RIE stop layer, no removal of the RIE stop layer around the main pole is necessary. Additionally, the leading edge shield and the side shield will magnetically join together without extra processing as there will be no magnetic separation between the leading edge shield and the side shield.

Abstract: According to one embodiment, a magnetic head includes a main pole configured to apply a recording magnetic field, a return pole opposed to a trailing side of the main pole across a write gap and configured to return magnetic flux from the main pole, a coil configured to excite magnetic flux in the main pole, a spin-torque oscillator located between respective facing surfaces of the return pole and an end portion of the main pole on the recording-medium side and configured to produce a high-frequency magnetic field, a current source configured to apply current to the spin-torque oscillator through the return and main poles, and a nonmagnetic layer provided in at least one of the poles and extending from a facing surface of the at least one of the poles, which faces the spin-torque oscillator, in a direction across the facing surface.

Abstract: Methods for fabrication of tapered magnetic poles with a non-magnetic front bump layer. A magnetic pole may have a plurality of tapered surfaces at or near an air bearing surface (ABS), wherein a thickness of the write pole increases in a direction away from the ABS. A non-magnetic front bump layer may be formed on one or more of the tapered surfaces of the magnetic pole at a distance from the ABS. The front bump layer may increase the separation distance between a shield layer and the magnetic pole near the tapered surface, thereby improving the performance of the write head.

Abstract: A magnetic head includes a main pole, a write shield, a return path section, a heater that generates heat for making part of a medium facing surface protrude, and a sensor that detects contact of the part of the medium facing surface with a recording medium. The return path section includes: a yoke layer located backward of the main pole along the direction of travel of the recording medium; a first coupling part coupling the yoke layer and the write shield to each other; and a second coupling part located away from the medium facing surface and coupling the yoke layer and the main pole to each other. The first coupling part has an end face facing toward the yoke layer. This end face includes a middle portion spaced from the yoke layer and facing the yoke layer, and two side portions located on opposite sides of the middle portion in a track width direction and in contact with the yoke layer. The sensor is located between the middle portion and the yoke layer.

Abstract: A PMR writer is disclosed with an all wrap around design wherein the leading shield, side shields, and composite trailing shield are comprised of an anisotropic (?Ku) magnetic layer, and where the leading shield and side shields adjoin a gap layer. The composite shield has a first layer made of an isotropic magnetic material adjoining the write gap, and the anisotropic (?Ku) layer adjoins the first trailing shield layer on a side opposite the write gap. The main pole may have a tapered leading side and a tapered trailing side with the anisotropic (?Ku) leading shield and trailing shield layers extending a greater distance from the ABS than the ends of the tapered main pole sides. Adjacent track erasure is minimized while on-track write field and field gradient are improved.

Abstract: In one embodiment, a magnetic head includes a main pole, a trailing shield positioned near a trailing side of the main pole, a side shield positioned near both sides of the main pole in a cross-track direction, a leading shield positioned near a leading side of the main pole, and a gap positioned between the main pole and the shields, characterized in that Sg1<Sg2, wherein Sg1 is a distance in the cross-track direction between a bending point of a leading edge of the trailing shield and a trailing corner of the main pole nearest to the bending point, and Sg2 is a distance in the cross-track direction between a first point on an edge of the side shield parallel in the cross-track direction to the trailing corner of the main pole and the trailing corner of the main pole nearest to the first point.

Abstract: A perpendicular magnetic read head having a balanced capacitive coupling with the substrate. The read head includes a magnetoresistive sensor with first and second magnetic, electrically conductive shields separated from a substrate by a layer of non-magnetic, electrically insulating material. A dummy magnetic shield is formed on the non-magnetic electrically insulating layer and is electrically connected with the second magnetic, electrically conductive shield. The dummy shield is formed to have a capacitive coupling with the substrate that matches the capacitive coupling of the first magnetic, electrically conductive shield with the substrate.

Abstract: A magnetic recorder includes: a magnetic recording medium; a reproducing head; a magnetic recording head including: a main magnetic pole; a first magnetic layer containing a TM alloy; a second magnetic layer containing a TM alloy or an RE-TM alloy; a third magnetic layer containing an RE-TM alloy; a first intermediate layer provided between the first magnetic layer and the second magnetic layer; and a second intermediate layer provided between the second magnetic layer and the third magnetic layer; and a signal processing portion which performs signal writing into the magnetic recording medium by using the magnetic recording head and reading from the magnetic recording medium by using the reproducing head.

Abstract: A perpendicular write head having a wrap around shield and a conformal side gap. In fabricating the write head, the leading edge shield may be chemical mechanical polished down to a level that is substantially even with a chemical mechanical polishing stop layer. Because the leading edge shield and the chemical mechanical polishing stop layer are used as RIE stop for trench RIE, a fully conformal side shield may be formed with a LTE/LES.

Abstract: A magnetic pole suitable for perpendicular magnetic recording is described. This write pole is symmetrically located relative to its side shields and has at least three additional surfaces that are disposed to lie in planes that are normal to the substrate's top surface.

Abstract: A magnetic writer comprises a write pole and a trailing shield. The write pole is proximate an air bearing surface. The trailing shield is separated from the write pole by a first write gap. The trailing shield is configured with a magnetic layer disposed between the first write gap and a second write gap.

Abstract: A write element for magnetic recording includes a main pole and a shield. The main pole has first and second sides with respect to a down-track direction. The shield at least partially surrounds the main pole with a continuously concave inner sidewall. The angle between the inner sidewall of the shield and the direction of motion of the write element is greater than the angle between the sides of the main pole and the direction of motion.

Abstract: According to one embodiment, a recording head includes a main pole configured to apply a recording magnetic field to a recording medium, a trailing shield opposed to the main pole with a gap therebetween, a spin-torque oscillator at least a part of which is located between the main pole and the trailing shield and configured to apply a high-frequency magnetic field to the recording medium, and an auxiliary oscillator configured to apply an auxiliary magnetic field to the spin-torque oscillator.

Abstract: According to one embodiment, a spin torque oscillator includes a field generation layer, a spin injection layer including a first layer and a second layer, and an interlayer interposed between the field generation layer and the spin injection layer, wherein the first layer is interposed between the second layer and the interlayer and includes a (001)-oriented Heuslar magnetic alloy or a (001)-oriented magnetic material having a body-centered cubic lattice structure.

Abstract: In a magnetic head to be used for a shingled recording method, degradation of a signal resolution and a decrease in a signal-to-noise ratio which are caused by an asymmetrical inter-bit transition curvature are prevented, and a low bit error rate is realized. A magnetic head includes a recording head and a reproducing head. The reproducing head includes a pair of magnetic shields and a sensor sandwiched between the pair of magnetic shields. The gap between the magnetic shields is formed so that the longitudinal direction thereof gets inclined by a certain angle with respect to a cross-track direction in line with the shape of a curvature of an inter-bit transition on an effective record track in a record pattern recorded on a recording medium.

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: Systems and methods for providing a write pole pedestal for microwave assisted magnetic recording systems are provided. One such system includes a magnetic transducer for microwave assisted magnetic recording, the magnetic transducer including a pole including a leading edge and a trailing edge, a trailing shield positioned closer to the pole trailing edge than the pole leading edge, and an energy transducer positioned between the pole trailing edge and the trailing shield, where a trailing parallel side of the trapezoid is smaller than a leading parallel side of the trapezoid.

Abstract: A method fabricates a side shield for a magnetic transducer having a nonmagnetic layer and an ABS location corresponding to an ABS. The nonmagnetic layer has a pole trench therein. The pole trench has a shape and location corresponding to the pole. A wet etchable layer is deposited. Part of the wet etchable layer resides in the pole trench. A pole is formed. The pole has a bottom and a top wider than the bottom in the pole tip region. Part of the pole in the pole tip region is in the pole trench on at least part of the wet etchable layer. At least parts of the wet etchable layer and the nonmagnetic layer are removed, forming an air bridge. The air bridge is between part of the pole at the ABS location and an underlying layer. Side shield layer(s) that substantially fill the air bridge are deposited.

Abstract: An apparatus includes a waveguide having a core layer and an end adjacent to an air bearing surface, first and second poles magnetically coupled to each other and positioned on opposite sides of the waveguide, wherein the first pole includes a first portion spaced from the waveguide and a second portion extending from the first portion toward the air bearing surface, with the second portion being structured such that an end of the second portion is closer to the core layer of the waveguide than the first portion, and a heat sink positioned adjacent to the second portion of the first pole.

Abstract: A magnetic write head having write pole and a wrap-around-trailing magnetic shield having side portions that are separated from the write pole by tapered non-magnetic side gap layers. The tapered non-magnetic side gap layers provide a non-magnetic side gap width that increases with increasing distance from the ABS, thereby providing optimal protection against adjacent track interference at the ABS while minimizing write field loss to the shield in regions away from the ABS.

Abstract: Methods for fabrication of tapered magnetic poles with a non-magnetic front bump layer. A magnetic pole may have a tapered surface at or near an air bearing surface (ABS), wherein a thickness of the write pole increases in a direction away from the ABS. A non-magnetic front bump layer may be formed on the tapered surface of the magnetic pole and away from the ABS. The front bump layer may increase the separation distance between a shield layer and the magnetic pole near the tapered surface, thereby improving the performance of the write head.

Abstract: According to one embodiment, a magnetic recording device includes a magnetic recording head and a magnetic recording medium. The magnetic recording head includes a main magnetic pole, a shield and a stacked structure. The main magnetic pole has a medium facing surface and a main magnetic pole side surface. The shield has a shield side surface. The stacked structure is provided between the main magnetic pole and shield, and includes first and second magnetic layers, and an intermediate layer. The magnetic recording medium includes a backing layer and a magnetic recording layer. A distance between an end portion of the medium facing surface on a side of the stacked structure and the backing layer is twice or more of a distance between the main magnetic pole side surface and the shield side surface.

Abstract: A magnetic write head having a write pole with a tapered trailing edge. The write head has a non-magnetic step layer and a non-magnetic bump formed on the front edge of the magnetic step layer. A non-magnetic trailing gap layer is formed over the tapered trailing edge of the write pole and over the non-magnetic bump and over the non-magnetic step layer. A magnetic trailing shield is formed over at least a portion of the non-magnetic gap layer.

Abstract: Embodiments in accordance with the present invention provide a magnetic head having a narrow track width and excellent in productivity for the purpose of realizing a disk storage unit having a large capacity. In a magnetic head having a plurality of flairs on a main magnetic pole, a side shield is formed via a non-magnetic film on both sides of the flair disposed close to an air bearing surface in such a fashion as to be aligned with the flair.

Abstract: A perpendicular magnetic recording (PMR) head is fabricated with a pole tip shielded laterally by a pair of symmetrically separated side shields that extend from an edge of a trailing edge shield to form a shield with the shape of a ?. The easy axis direction of the side shields is in the in-track direction. As a result, the side shields effectively shield the fringing fields of the magnetic pole tip from causing adjacent track erasures, while not adding their own fringing fields that could cause erasures even beyond adjacent tracks.

Abstract: A magnetic recording head for perpendicular magnetic recording includes energizing means, a recording pole, and a return pole. The recording pole narrows to a tip region with leading and trailing write edges separated by first and second side edges. The tip region provides a low reluctance path for magnetic flux generated by the energizing means. The return pole has a shield flare projecting towards the trailing write edge. A gap separates a leading edge of the shield flare from the trailing write edge. The shield flare diverts magnetic flux from reaching the tip region, thereby shielding the recording medium beneath the shield flare from the magnetic field while the side edges of the tip region and the recording medium beneath the gap are unshielded. A rear flare smoothes the discontinuity at the trailing edge of the return pole, thus reducing the peak magnetic field under the return pole.

Abstract: A method for forming a magnetic write head having a trailing shield with a tapered and stepped, self aligned trailing magnetic shield. The shield has a tapered portion that tapers away from the write pole as it extends away from the ABS. This tapered portion helps to channel flux to the pole tip portion of the shield, while preventing the loss of write field to the shield. The stepped portion of the shield further helps to prevent the loss of write field and also defines a secondary throat height of the shield that can be accurately located relative to the air bearing surface.

Abstract: A magnetic head comprises a main pole, a return pole and a magnetic damper. The main pole is configured to emit flux and the return pole is configured to return the flux to the main pole. The magnetic damper is inductively coupled to the return pole and comprises a first conductor spaced from a first side of the return pole, a second conductor spaced from a second side of the return pole and a third conductor connecting the first conductor to the second conductor.