Abstract: A hard disk drive is disclosed with a slider containing a Flying height On Demand (FOD) heater using two heater sheets configured to be driven by electric currents flowing in essentially opposite directions, causing the magnetic field induced by the FOD heater to be much smaller than prior art FOD heaters using just one sheet with a single current direction. Also disclosed are the slider, the head gimbal assembly, and the head stack assembly, where both assemblies include at least one instance of the slider. Also disclosed, the methods of operating the hard disk drive and the slider and making the slider, the head gimbal assembly, the head stack assembly and the hard disk drive.

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 method in one embodiment includes forming an electric lapping guide layer; forming a write pole; forming a first gap layer over the write pole; masking a portion of the first gap layer for defining a window over the write pole and at least a portion of the electric lapping guide layer; and forming a bump over the write pole in the window. A system in one embodiment includes an electric lapping guide layer; a write pole positioned to one side of the electric lapping guide layer; and a bump formed over the write pole in a window, wherein a back end of the electric lapping guide layer and a front end of the bump are about a same distance from a lapped surface of a head. Additional methods and systems are presented.

Abstract: A method in one embodiment includes applying a current to a lead of a tunneling magnetoresistance sensor for inducing joule heating of the lead or a heating layer, the level of joule heating being sufficient to anneal a magnetic layer of the sensor; and maintaining the current at the level for an amount of time sufficient to anneal the tunneling magnetoresistive (TMR) sensor. A system in one embodiment comprises a first lead coupled to one end of a tunneling magnetoresistance sensor stack; a second lead coupled to another end of the sensor stack; and a third lead coupled to the first lead, the third lead being selectively coupleable to a ground, wherein a current applied to the first lead at a predetermined level when the third lead is coupled to the ground induces joule heating of the first lead or a heating layer coupled to the first and third leads, the joule heating applied for a predetermined amount of time being sufficient to anneal a magnetic layer of the sensor.

Abstract: The invention concerns a magnetic field-sensitive component, a magnetic field sensing device and a memory structure each incorporating said component, and a method for detecting a magnetic field using said component. A component according to the invention comprises: at least one diluted magnetic semiconductor, first means for generating an electric current in said semiconductor along one predetermined direction, and second means for producing a signal representing a Hall voltage transverse to said direction, and it is so designed that the semiconductor is selected from the group consisting of II/VI and IV/IV type semiconductors and comprises a zone sensitive to said field which forms all or part of a magnetic quantum well, wherein are confined current carriers incorporated by doping in the semiconductor and inducing in said well ferromagnetic exchange interactions.

Abstract: A system according to one embodiment comprises a head having a perpendicular writer, the writer comprising: a first pole structure having a pole tip positioned towards an air bearing surface of the head, the first pole structure having a portion that is recessed from an extent of the pole tip closest the air bearing surface; a return pole having an end positioned towards the air bearing surface of the head; and a gap between the first pole structure and the return pole, wherein the recessed portion is recessed less than about 1.25 microns relative to the extent of the pole tip closest the air bearing surface. Additional embodiments as well as methods are presented.

Abstract: A magnetoresistive reader having a sensor, current contacts with low parasitic resistance and a top shield with substantially planar topology is fabricated by first defining a stripe height back edge of the sensor. Next, a reader width of the sensor is defined. The current contacts are deposited to a thickness such that a top surface of the current contacts is substantially level with a top surface of the sensor. The top shield is deposited over the sensor and the current contacts. Defining the stripe height back edge prior to the reader width results in current contacts with low parasitic resistance and inhibits the formation of magnetic domains in the top shield.

Abstract: A magnetic element has a first magnetic material exhibiting thermal fluctuation of magnetization which depends on an external magnetic field and generates spin fluctuation in conduction electrons; a nonmagnetic conductive material which is laminated on the first magnetic material and transfers the conduction electrons; a second magnetic material which is laminated on the nonmagnetic conductive material and generates a magnetic resonance upon injection of the conduction electrons; a first electrode electrically coupled with the first magnetic material; and a second electrode electrically coupled with the second magnetic material.

Abstract: A magnetic head in one embodiment comprises a plurality of components separated from each other by insulative portions; and at least one connective element coupling the components together. A magnetic tape head in another embodiment comprises a substrate; a closure separated from the substrate by an insulative portion; and at least one connective element coupling the substrate and closure together.

Abstract: A method for reducing thin film media layer thickness while maintaining adequate magnetic recording performance includes providing a substrate comprising a rigid support structure, depositing a soft underlayer on top of the substrate, depositing an interlayer on top of the soft underlayer and depositing a exchange break layer on top of the interlayer, wherein the exchange break layer comprises a flash layer of RuTi and a seed layer of Ru. The flash layer is deposited in place of a pure Ru layer, thereby reducing the amount of Ru deposited as well as decreasing the thickness of the overall intermediate layer. The magnetic performance of the media is maintained with the substitution of a RuTi flash layer for a pure Ru layer.

Abstract: A method for manufacturing a magnetostrictive torque sensor having low nonuniformity of sensitivity characteristics. The residual austenite content in the rotating shaft of the torque sensor is measured first. A magnetic film is subsequently subjected to a heat treatment under heat treatment conditions that are different for each of the measured residual austenite contents, and magnetic anisotropy is imparted.

Abstract: A method for testing magnetic heads formed on a wafer to detect the presence of thermal induced popcorn noise resulting from thermal fly height control. The method includes performing a quasi test on a magnetic head, the quasi test being performed over 400 or more cycles of magnetic field application. For additional test accuracy, the write head can be cycled while 400 or more cycles of magnetic field are generated.

Abstract: A magnetoresistive effect element includes a first ferromagnetic layer, Cr layer, Heusler alloy layer, barrier layer, and second ferromagnetic layer. The first ferromagnetic layer has the body-centered cubic lattice structure. The Cr layer is formed on the first ferromagnetic layer and has the body-centered cubic lattice structure. The Heusler alloy layer is formed on the Cr layer. The barrier layer is formed on the Heusler alloy layer. The second ferromagnetic layer is formed on the barrier layer.

Abstract: The present invention relates to a magnetic recording medium comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support. The magnetic layer has a thickness ranging from 30 to 130 nm, and a glossiness of the magnetic layer surface ranges from 155 to 270 percent.

Abstract: In one embodiment, a magnetic head includes a substrate having a media support surface; a gap coupled to the substrate, the gap having at least one of a magnetoresistive (MR) sensor and a writer; a closure coupled to the gap on a side thereof opposite the substrate, said closure forming a portion of the media support surface; and a material formed in one or more recesses extending into the media support surface of at least one of the substrate and the closure.

Abstract: A current determiner comprising a first input conductor and a first current sensor, formed of a plurality of magnetoresistive, anisotropic, ferromagnetic thin-film layers at least two of which are separated from one another by a nonmagnetic layer positioned therebetween, and both supported on a substrate adjacent to and spaced apart from one another so they are electrically isolated with the first current sensor positioned in those magnetic fields arising from any input currents. A first shield/concentrator of a material exhibiting a substantial magnetic permeability is positioned between the substrate and the first input conductor. A similar second current sensor can be individually formed, but can also be in the current determiner structure that is supported on the substrate along with a second input conductor supported on the substrate suited for conducting input currents therethrough.

Abstract: Localized temperature increases inside integrated circuits due to heating at operation are prevented or controlled by electronic devices or wirings with CPP (current-perpendicular-to-plane) structures which have a current cooling effect. A CPP structure refers to a structure comprising a columnar electrically conductive portion and an insulator portion surrounding the conductive portion. The columnar portion is formed from a multilayered structure in a direction perpendicular to the plane of the layers, so as to allow a current to flow from an upper layer to a lower layer (or vice versa). The cooling effect is induced by current at the interface (or a plural of interfaces) of appropriately selected different kinds of materials (which are conductive substances in general, such as metals, semiconductors, and alloys thereof) in the columnar portion due to the Peltier effect when a current flows through the column. Temperature in a minute range is detected by a thermocouple with the CPP structure.

Abstract: A method of making a magnetoresistive sensor includes defining a track width of a magnetoresistive element stack of the sensor. Further, processes of the method enable depositing of hard magnetic bias material on each side of the stack. These processes may permit both milling of excess depositions of the material outside of regions where the hard magnetic bias material is desired via use of a photoresist and making the material have a planar surface via chemical mechanical polishing, which also removes the material on top of the stack.

Abstract: A magnetic write head for perpendicular magnetic recording. The write head has a secondary flare point defined by magnetic structures that extend from the sides of the write pole, but not over the trailing edge of the write pole. The magnetic structures each have a front edge that defines the secondary flare point. By constructing the magnetic structures so that they only extend from the sides of the write pole and not over the write pole, they can be formed by electroplating, while leafing the mask structure (used to define the write pole) still intact, thereby greatly simplifying manufacture and preventing damage to the write pole during manufacture.

Abstract: A combined manufacturable wafer and test device for measuring a tunneling-magnetoresistance property of a tunneling-magnetoresistance, sensor-layer structure. The combined manufacturable wafer and test device comprises a tunneling-magnetoresistance, sensor-layer structure disposed on a substrate. The combined manufacturable wafer and test device also comprises a plurality of partially fabricated tunneling-magnetoresistance sensors; at least one of the partially fabricated tunneling-magnetoresistance sensors is disposed at one of a plurality of first locations. The test device is disposed on the substrate at a second location different from the plurality of first locations. The test device allows measurement of the tunneling-magnetoresistance property of the tunneling-magnetoresistance, sensor-layer structure using a current-in-plane-tunneling technique.

Abstract: A magnetic sensor having at least a first and at least a second structure of soft-magnetic material that are spatially separated and define a first gap therebetween. The first and second structure of soft-magnetic material are adapted to form a gap magnetic field pointing in a direction substantially perpendicular to the elongation of the first gap in the vicinity of the first gap in response to an external magnetic field. Additionally, the magnetic sensor comprises at least a first magnetoresistive layered structure that is positioned in the vicinity of the first gap including inside the first gap and that is sensitive to the gap magnetic field.

Abstract: Provided is a thin-film magnetic head for reading data from a magnetic recording medium and/or writing data to a magnetic recording medium, in which the magnetic spacing can be controlled appropriately by stably adjusting the pressure working between the thin-film magnetic head and the magnetic recording medium according to the change of conditions such as the change over time. This thin-film magnetic head comprises at least one through hole reaching a surface opposed to the magnetic recording medium of the thin-film magnetic head, for adjusting a pressure working between the thin-film magnetic head and the magnetic recording medium. Preferably, the head further comprises at least one flow-amount control means for controlling the flow amount of gas that flows via the at least one through hole.

Abstract: A head IC adjusts an amplitude level of a read signal of a head and outputs the adjusted signal to a read channel having an AGC amplifier. A head IC includes: a differential amplifier; an AGC circuit; external gain setting sections; and a switch. The AGC amplifier is disposed in the head IC, and the amplitude from the head is automatically adjusted in the head IC. The signal level can be adjusted within the input dynamic range of the AGC amplifier of the read channel. An estimated gain value converted from a result of measuring a resistance value of the head is used as an initial value for the adjustment of the AGC amplifier. It becomes possible attempting to prevent an increase in the lock-in times of the AGC, to guarantee stability, and to prevent judgment errors of the AGC.

Abstract: The thickness of an antiferromagnetic layer (IrMn) and the thickness of a nonmagnetic interlayer (Cu) are adjusted so as to be within the area surrounded by boundaries a to f on the graph of FIG. 6 in which the horizontal axis represents the IrMn film thickness and the vertical axis represents the Cu film thickness. Consequently, the interlayer coupling magnetic field Hin can be made to be 10 Oe or more, and the variation in the interlayer coupling magnetic field Hin can be made to be 2 Oe or less. In addition, in the area surrounded by boundaries a to f, at any IrMn film thickness, the Cu film thickness range in which the variation can be made to be 2 Oe or less can be set over a wide range, as compared with a known structure.

Abstract: The present invention provides apparatus and method for controlling the asymmetrical properties of the response of a magnetic sensor element to a magnetic field produced by the digital data in a magnetic storage device. The present invention also provides an apparatus and method for controlling the bias point of a magnetic field produced by a magnetic sensor element.

Abstract: The read-head is capable of corresponding to high recording density without deteriorating characteristics even if a small size read-element is used. The read-head of the present invention comprises: a read-element including a free layer; and a magnetic domain control layer for domain-controlling the free layer. The magnetic domain control layer is composed of a soft magnetic material including at least one substance selected from the group consisting of Fe, Co and Ni. A ratio (a/b) of a length (a) of the magnetic domain control layer in the core width direction to a length (b) thereof in the height direction is 5 or more, and the length (b) is 100 nm or less.

Abstract: A Lorenz magnetoresistive sensor having a pair of voltage leads and a pair of current leads. The voltage leads are located at either side of one of the current leads and are separated by a distance that is substantially equal to the length of a bit to be measured. The Lorenz magnetoresistive sensor can be, for example an extraordinary magnetoresistive sensor having a quantum well structure such as a two dimensional electron gas and a shunt structure formed on an edge of the quantum well structure opposite the voltage and current leads.

Abstract: Disclosed herein is a position sensor including, a magnetic recording medium including two incremental layers and an absolute layer, the absolute layer provided between the incremental layers, each of the layers having magnetic information recorded therein, and a magnetic detection section including three magnetoresistance effect devices opposite to the layers of the magnetic recording medium, being moved relative to the magnetic recording medium in the extending direction of the layers, and being operative to detect the magnetic information in the layers by the magnetoresistance effect devices.

Abstract: An MTJ in an MRAM array or TMR read head is disclosed in which a capping layer has a bilayer configuration with a non-magnetic NiFeX inner layer on a NiFe free layer and a Ta layer on the NiFeX layer to improve dR/R and minimize magnetostriction. Optionally, a trilayer configuration may be employed where the Ta layer is sandwiched between an inner NiFeX layer and an outer Ru layer. The X component in NiFeX is preferably an element having an oxidation potential greater than Ni or Fe such as Mg, Hf, Zr, Nb, or Ta. NiFeX is preferably formed by co-sputtering a NiFe target with an X target at a forward power of about 200 W and 50 W, respectively. In an MRAM structure, the Mg content in NiFeMg may be increased to >50 atomic % to improve the gettering power of removing oxygen from the free layer.

Abstract: The invention relates to a vertical magnetic recording head that records information on a recording medium, such as a magnetic disk, and a magnetic recording apparatus using the same. An object of the invention is to provide a vertical magnetic recording head capable of preventing the leakage of a magnetic field without deteriorating a recording performance and a magnetic recording apparatus using the same. A vertical recording magnetic head is mounted on a slider having a medium facing surface, and includes a main magnetic pole that includes a leading end exposed from the medium facing surface; and side shields that are separated from the side surface of the leading end by a first distance and are retreated from the medium facing surface by a second distance.

Abstract: Provided is a vertical magnetic recording head having a main pole, a return yoke, and a coil, all of which are formed on a substrate, and a method of manufacturing the same. The main pole includes a vertical portion which is vertical to the substrate, a horizontal portion that connects a lower part of the vertical portion to the return yoke, and a main pole tip formed on the vertical portion of the main pole. The main pole tip has a conical shape vertical to the substrate.

Abstract: It is made possible to provide a magnetic head that generates a sufficient high-frequency magnetic field for assisting recording operations, and a magnetic recording device that includes the magnetic head. A magnetic head includes: a recording magnetic pole; a return yoke magnetically coupled to the recording magnetic pole; and at least two spin torque oscillators provided near the recording magnetic pole.

Abstract: According to an aspect of an embodiment, a head slider includes: a slider substrate; and an operating unit arranged on the slider substrate, the operating unit having a pair of electrodes and a piezoelectric component arranged between the pair of electrodes, the pair of electrodes being constituted by a first electrode and a second electrode, in which the product of the Young's modulus and the thickness of the first electrode in the direction from the first electrode to the second electrode is larger than the product of the Young's modulus and the thickness of the second electrode in the direction from the first electrode to the second electrode. The head slider further includes a magnetic head arranged on the slider substrate with the operating unit, opposite to the slider substrate.

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.

Abstract: An Extraordinary Magnetoresistive Sensor (EMR Sensor) having wide voltage lead tabs for reduced noise and increased signal to noise ratio. The leads can be formed in a triad structure, wherein a pair of voltage leads is located at either side of a current lead, or can be formed in a diad structure having a single voltage lead located at one side of a current lead.

Abstract: A perpendicular magnetic recording (PMR) head and a method of manufacturing the same are provided. The PMR head includes: a main pole; a coil enclosing the main pole as a solenoid type to allow the main pole to generate a magnetic field required for recording data on a recording medium; and a return yoke forming a magnetic path of a magnetic field together with the main pole and having a throat disposed opposite the main pole with a gap between the return yoke and the main pole. One end of the gap disposed near an air bearing surface (ABS) is thinner than the other end of the gap, such that the throat tapers from the other end of the gap to the one end of the gap.

Abstract: An extraordinary magnetoresistive device EMR sensor that is capable of reading two separate tracks of data simultaneously. The EMR sensor has a semiconductor structure with an electrically conductive shunt structure at one side. The other side of the semiconductor structure is connected with a pair of current leads. Each of the current leads is disposed between a pair of voltage leads. Each pair of voltage leads is capable of independently reading a magnetic signal by measuring the voltage potential change across the pair of voltage leads. The EMR structure minimizes the number of leads needed to read two magnetic signals by using a single pair of current leads to read two tracks of data.

Abstract: According to one embodiment, a disk drive having a spin torque oscillator and designed to perform high frequency assisted writing. The disk drive has a magnetic disk, a magnetic head, a coil, and a drive current controller. The drive current controller controls a drive current to supply to the spin torque oscillator. To record data magnetically in the disk, the drive current controller supplies to the spin torque oscillator the drive current that changes in synchronism with the polarity inversion of the recording current supplied to the coil, which excites the recording magnetic pole of the magnetic head.

Abstract: According to an aspect of an embodiment, an storage device includes a storage medium having a substrate, a storage medium layer for storing information, a first lubricating layer on a first area of the storage medium layer, and a second lubricating layer on a second area of the storage medium, the second lubricating layer having a viscosity lower than the first lubricating layer. The storage device further comprises a head for writing information into the storage medium layer or reading information from the storage medium layer.

Abstract: A spin FET of an aspect of the present invention includes source/drain regions, a channel region between the source/drain regions, and a gate electrode above the channel region. Each of the source/drain regions includes a stack structure which is comprised of a low work function material and a ferromagnet. The low work function material is a non-oxide which is comprised of one of Mg, K, Ca and Sc, or an alloy which includes the non-oxide of 50 at % or more.

Abstract: While an emitting position of light from an optical waveguide and a magnetic pole end part are made closer to each other, high-density writing onto a magnetic recording medium is realized. A thermally assisted magnetic head comprises a main magnetic pole layer having a magnetic pole end part exposed at a medium-opposing surface opposing a magnetic disk, and an optical waveguide for deflecting laser light incident thereon into a laminating direction. The main magnetic pole layer is positioned on a side where the light is deflected by the optical waveguide. The magnetic pole end part projects to the side where the light is deflected by the optical waveguide. The optical waveguide projects more than the magnetic pole end part on the medium-opposing surface side.

Abstract: A PMR writer is disclosed that minimizes pole erasure during non-writing and maximize write field during writing through an AFM-FM phase change material 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 comprised of a laminated structure having a plurality of “n” ferromagnetic layers and “n-1” AFM-FM phase change material layers arranged 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 %. AFM-FM phase change material may also be used as a flux gate to prevent yoke flux from leaking into the write pole tip. Heating for the AFM to FM transition is provided by write coils and/or a coil located near the AFM-FM phase change material to enable faster transition times.

Abstract: A method of reading magnetic data from a magnetically-activatable sheet product carrying magnetic data. The product comprises a pair of laminated outer sheets between which is a magnetic layer comprising magnetically-activatable particles in a binder matrix. For reading the data, a thin-film magnetoresistive sensor is used in which the shape anisotropy of the sensor is enhanced in a direction transversely to the longitudinal axis of the sensor.

Abstract: A magnetic field sensor device comprising a substrate having at least a first tilted planar section having a surface normal at a first angle with respect to a surface normal of the substrate, and at least a first magnetoresistive layered structure positioned at the at least first tilted section. Methods for manufacturing magnetic field sensor devices are also presented.

Abstract: The thin-film magnetic head of the invention comprises a magneto-resistive effect device including a multilayer film and a bias mechanism portion including a bias magnetic field-applying layer formed on each widthwise end of the multilayer film. When the magneto-resistive effective device including a multilayer film and the bias mechanism portion are viewed in plane on their own, the uppermost extremity of the rear end of the magneto-resistive effect device and the uppermost extremity of the rear end of the bias mechanism portion lie at substantially the same depth-wise position, and the rear slant of the bias mechanism portion is gentler in gradient than the rear slat of the magneto-resistive effect device. It is thus possible just only to facilitate the fabrication of the device but also to achieve several advantages of being a lower rate of occurrence of noise, higher reliability and higher yields.

Abstract: To provide a magnetic reading head that features high resolution and low noise, and that can support a hard disk with terabit-level surface recording density. A current is caused to flow from a pinned layer with its magnetization direction fixed by an antiferro magnetic material, to a non-magnetic thin wire having a portion affected by an external magnetic field and a portion not affected by the external magnetic field, so that spin polarized electrons are accumulated in the non-magnetic thin wire. A distance between voltage terminals of a voltmeter is set to less than the spin diffusion length of the non-magnetic thin wire. A change in the external magnetic field modulates some of the accumulated spin polarized electron, but does not others. Accordingly, an electrical potential difference depending on the external magnetic field is generated between the both end surfaces of the non-magnetic thin wire, and measured with the voltmeter.

Abstract: A magnetic sensor includes a magnetoresistance element having a peak of a thermal fluctuation strength of magnetization under a magnetic field having a certain frequency, a frequency filter connected to the magnetoresistance element and having its transmittance decreased or increased in substantially the frequency of the magnetic field to output a signal corresponding substantially to the peak of the thermal fluctuation strength of magnetization, and a detector connected to the frequency filter to detect the magnetic field based on the signal of the frequency filter.

Abstract: One illustrative method of fabricating a read sensor of a magnetic head includes the steps of forming a plurality of read sensor layers on a wafer; etching the read sensor layers to form a read sensor structure with a trench in front of the read sensor structure; forming a highly porous material within the trench; and slicing the wafer and lapping the sliced wafer through the highly porous material until an air bearing surface (ABS) of the magnetic head is reached. Advantageously, the highly porous material in front of the read sensor structure reduces mechanical stress on the read sensor during the lapping process. This reduces the likelihood that the amplitude of the read sensor will be degraded or set in a “flipped” or reversed orientation, as well as reduces the likelihood that electrostatic discharge (ESD) damage to the read sensor will occur.

Abstract: An extraordinary magnetoresistive device EMR having a discontinuous shunt structure. The discontinuous shunt structure improves the linearity of response of the EMR device. The EMR device includes a EMR heterostructure that includes an EMR active layer. The heterostructure can include first, second and third semiconductor layers, with the second layer being sandwiched between the first and third layers. The middle, or second semiconductor layer provides a two dimensional electron gas. The heterostructure has first and second opposed sides, with a pair of voltage leads and a pair of current leads connected with the first side of the structure. The discontinuous shunt structure is connected with the second side of the structure and may be in the form of a series of discontinuous, electrically conductive elements, such as semi-spherical gold elements.

Abstract: The magnetic signal reproduction system comprises a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support; and a reproduction head, wherein a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 ?m2, a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0, a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent, and the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer.