WO1993012928A1 - Supports d'enregistrement magnetiques comportant un materiau magnetique doux - Google Patents

Supports d'enregistrement magnetiques comportant un materiau magnetique doux Download PDF

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Publication number
WO1993012928A1
WO1993012928A1 PCT/US1992/010485 US9210485W WO9312928A1 WO 1993012928 A1 WO1993012928 A1 WO 1993012928A1 US 9210485 W US9210485 W US 9210485W WO 9312928 A1 WO9312928 A1 WO 9312928A1
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WIPO (PCT)
Prior art keywords
layer
magnetic recording
magnetic
recording medium
nonmagnetic
Prior art date
Application number
PCT/US1992/010485
Other languages
English (en)
Inventor
William B. Reed
Dennis R. Hollars
Robert B. Zubeck
Hyung J. Lee
Frank R. Reynen
Keith A. Ward
Maureen D. Klatt
Nancy A. Pope
Albert L. W. Hartman
Original Assignee
Conner Peripherals, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Conner Peripherals, Inc. filed Critical Conner Peripherals, Inc.
Priority to JP5511674A priority Critical patent/JPH07503337A/ja
Priority to EP19930900873 priority patent/EP0619776A4/fr
Publication of WO1993012928A1 publication Critical patent/WO1993012928A1/fr

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8408—Processes or apparatus specially adapted for manufacturing record carriers protecting the magnetic layer
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
    • G11B5/66—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers
    • G11B5/676—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers having magnetic layers separated by a nonmagnetic layer, e.g. antiferromagnetic layer, Cu layer or coupling layer
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/72—Protective coatings, e.g. anti-static or antifriction
    • G11B5/727—Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon

Definitions

  • the present invention relates to magnetic recording media, and more specifically, to multilayered horizor ⁇ al recording media incorporating a highly magnetically permeable material.
  • Conventional recording media include magnetic recording disks, tapes and "floppy" disks and typically have a multiple layer configuration.
  • the base of a magnetic recording medium is a substrate, commonly a nickel-phosphorus-plated aluminum disk or thermoplastic tape or film, mechanically supporting one or more layers of magnetic material.
  • a protective layer may be provided to prevent abrasion of the magnetic material by the magnetic head, or corrosion.
  • Data is stored magnetically on recording media by creating, with a magnetic head and a current, a pattern of magnetization zones within the magnetic layer. Zone boundaries, defined by magnetic flux reversals within the magnetic layer, represent the data. The amount of data stored therefore depends in great part on the ability of the magnetic material to support distinct, closely spaced lux reversals.
  • Magnetic materials may be characterized according to the orientation of the easy axis of magnetization. This orientation is the direction within the crystalline structure of the magnetic material that minimizes the energy density associated with the orientation of magnetic dipoles in the magnetic layer.
  • the easy axis of magnetization is perpendicular to the surface of the layer of magnetic material.
  • the easy axis of magnetization is parallel to the surface of the magnetic layer.
  • Horizontal recording media currently in use in conventional disk drives typically achieve linear bit densities on the order of 45,000 flux changes per inch (45 kfci) .
  • Selection of a suitable magnetic material may be " aided by reference to the hysteresis or "BH" loop for the material produced by an applied magnetic field, H.
  • H an applied magnetic field
  • the degree of magnetization induced in a magnetic material and the corresponding signal strength of data stored therein can be increased by using as the magnetic recording film a material with a greater magnetic moment.
  • a relatively thinner layer of a magnetic material with a relatively higher moment can provide a signal of the same strength as a thicker layer of a magnetic material with a relatively lower magnetic moment.
  • Other benefits realized by use of the higher moment material include more uniform magnetic field strength detected by the head and more sharply defined magnetic transitions, allowing a higher recorded data density.
  • the squareness of a magnetic recording material indirectly measures the potential magnitude of a signal retained in a magnetic material once the applied magnetic field is reduced or removed.
  • H c Another important feature of a magnetic material depicted in its BH loop is coercivity, H c .
  • H c is greater than several hundred Oersted (Oe)
  • the magnetic material is considered "hard”, like cobalt alloys and some oxides of chromium and iron. These materials tend to retain induced magnetization making them suitable for magnetic recording materials.
  • H c is on the order of a few Oe.
  • the coercivity measures the field necessary to demagnetize a magnetic material and is desirably of such a magnitude that data may be overwritten relatively easily while avoiding spontaneous erasure upon encountering a stray magnetic flux.
  • the manufacturing process als .lays a significant role in determining the .es of a magnetic recording medium.
  • substrate surface treatments such as texturization of disks, and the method and parameters of the deposition of the magnetic layers are often critical to the development of microscopic structures that permit and enhance magnetic recording properties.
  • NiFe layers of different thicknesses are deposited on either side of a thermoplastic film substrate to suppress outgassing from and thermal degradation of the film before deposition of the vertical recording layer.
  • the latter patent describes the adjustment of the composition of a NiFe layer (3000A - 10,OO ⁇ A), underlying a vertical recording layer, in order to reduce magnetic anisotropy- induced signal fluctuations.
  • NiFe layer as a 'keeper'-.
  • the 70 ⁇ A NiFe lies above a 1000 Oe ele ⁇ troless cobalt-phosphorus magnetic film reportedly to effectively eliminate the losses in output signal due to the physical space or air gap between the head and the medium during the read process.
  • reduction in spacing and reproduce gap losses is specifically attributed to the direct contact required between the NiFe and the magnetic recording layers.
  • the magnetic flux from the data stored in the directly underlying magnetic film is retained or 'keepered' by the overlying NiFe layer. No flux is detected by the head and therefore, no signal is read.
  • the paper states that when a bias is applied to the head, regions of the NiFe layer beneath the head become saturated.
  • an advantage is obtained by the simple alteration of the structure of a conventional magnetic recording medium. That is, by the deposition of a soft magnetic layer directly on a magnetic recording layer and application of a saturating bias flux, spacing and reproduce gap losses can be reduced sufficiently to allow increased data densities without reducing the actual head flying height or requiring a head with a narrower gap.
  • the configuration of the head with respect to the magnetic recording disk impacts the strength of the readback signal.
  • the physical separation between the flying head and the surface of the disk contributes to losses in the output signal.
  • spacing loss results from the decreasing contribution of flux from a particular bit to the output signal detected by the head as the separation increases.
  • the configuration of the head itself plays an important role in the successful reproduction of the signal representing previously recorded data.
  • TF thin film
  • finite pole heads used in hard disk drives, for example, one source of loss in output signal is due to finite pole effects. These effects come into play as the head sweeps across a particular magnetic transition in order to read it.
  • the edges of the head poles can sense signals from adjacent magnetic transitions, interfering with the signal from the magnetic transition or "bit" intended to be read.
  • This loss in output signal tends to recur periodically as the size of the magnetic transitions decreases, that is, as the data density increases. Therefore, instead of a smooth curve representing the decreasing output signal with increasing data density, the curve manifests "head bumps" where the length of the magnetic transitions approximates that of the pole thickness.
  • Expensive solutions e.g., the dedication of significant drive electronics, such as by the addition of filters, have been used to reduce finite pole effects. With the increasing use of TF heads in present and future disk drives and the push toward higher data densities, the loss in output signal due to finite pole effects represents a significant problem.
  • Gap length or gap "null" effects also cause significant loss of signal.
  • the poles may not effectively discern between the signals representing each bit. Instead, upon playback, the signal from one bit almost cancels that from the adjacent bit because of the combined effects of their constructive and destructive phase interferences. As a result, the output signal is virtually eliminated, producing nulls at these points as the data density increases, contributing to an increased error rate for the drive.
  • spacing loss 55 d/ ⁇ , where d is the distance between the head and the medium, and ⁇ is the recording signal wavelength. This equation has been used as a basis for predicting spacing losses for other magnetic recording media such as floppy and "hard" disks.
  • a general purpose of the present invention is to provide a magnetic recording medium that has improved magnetic recording properties.
  • a magnetic recording medium invention including a substrate, a magnetic recording layer overlying the substrate, a nonmagnetic layer directly overlying the magnetic recording layer and a soft magnetic layer overlying the nonmagnetic layer.
  • the nonmagnetic layer is deposited between the magnetic recording and soft magnetic layers such that upon application of a saturating bias flux, flux lines from the data stored in a particular bit, otherwise retained by the layer of soft magnetic material above the bit in the form of a closed path, open up to 'leak' along the layer of soft magnetic material and toward the head. Flux lines from all other bits remain keepered. The leaking flux couples with the head even at significant distances relative to the distance between the disk and the head.
  • An advantage of the present invention is that it obtains a magnetic recording medium with increased data storage capacity compared with conventional magnetic recording media.
  • An additional advantage of the present invention is that it provides a magnetic recording medium that has improved signal strength compared with that obtained from conventional recording media.
  • Another advantage of the present invention is that it provides a magnetic recording medium with improved signal-to-noise characteristics.
  • a further advantage of the present invention is that it obtains reduced spacing loss.
  • Another advantage of the present invention is that it improves the efficiency of the magnetic recording head during read and write operation.
  • An additional advantage of the present invention is that the magnetic recording medium exhibits significantly reduced phase interferences of the bit pattern.
  • a further advantage of the present invention is that the magnetic recording medium exhibits reduced losses in output signal due to finite pole and gap null effects.
  • Another advantage of the present invention is that the magnetic recording medium has improved bit shift characteristics.
  • An additional advantage of the present invention is that provision of additional, readily compatible layers in a multi-layer magnetic recording medium, including a thin layer of soft magnetic material, substantially enhances the magnetic recording properties of a magnetic recording medium.
  • a further advantage of the present invention is that interposition of a thin nonmagnetic layer between a soft magnetic material and a horizontal magnetic recording medium substantially enhances the magnetic recording properties of a magnetic recording medium.
  • Another advantage of the present invention is that the output signal is less sensitive to head flying height variations resulting from roughness of the medium surface.
  • the present invention may be practiced with a wide variety of horizontal or vertical recording materials, soft magnetic materials, nonmagnetic materials and substrates.
  • conventional deposition methods may be employed to prepare the magnetic recording media of the present invention.
  • the above-described advantages may be achieved by the addition of a thin, low cost nonmagnetic ' layer using existing fabrication techniques and equipment.
  • Figure 1 is a cross-section of a magnetic recording medium in which a magnetic recording layer directly contacts a soft magnetic layer, as described in the prior art
  • Figure 2 illustrates the reported frequency response for the magnetic recording medium prepared and tested according to the prior art
  • Figure 3 illustrates the observed frequency response for the magnetic recording medium prepared as reported in the prior art
  • Figure 4 is a cross-section of a magnetic recording medium according to the present invention.
  • Figures 5 and 6 illustrate comparisons of the frequency responses of a conventional magnetic recording medium and a magnetic recording medium according to the present invention
  • Figure 7 illustrates the spacing loss relationships for a conventional medium and a magnetic recording medium according to the present invention
  • Figure 8 illustrates the noise characteristics of a conventional magnetic recording medium
  • Figure 9 illustrates the noise characteristics of a magnetic recording medium according to the present invention
  • Figure 10 illustrates, the bit shift characteristics of a conventional magnetic recording medium
  • Figure 11 illustrates the bit shift characteristics of a magnetic recording medium according to the present invention
  • Figure 12 is an isolated pulse plot of a conventional magnetic recording medium
  • Figure 13 is an isolated pulse plot of a magnetic recording medium according to the present invention.
  • Figure 14 illustrates a schematic representation of a two-dimensional computer model used to study the interaction of a conventional TF head with a conventional magnetic recording medium and a magnetic recording medium having a soft magnetic layer overlying the magnetic recording layer according to the present invention
  • Figures 15A and 15B illustrate magnified views of the magnetic exchange coup.! - ' i between the TF head and the conventional magnetic r ding medium;
  • Figures 16A and 16B ustrate magnified views of the magnetic exchange coup " , g between the TF head and the magnetic recording medium with a soft magnetic layer overlying the recording layer according to the esent invention
  • Figure 17 illustrates a BH loop for a conV urional magnetic recording medium
  • Figure 18 is a BH loop for a magnetic recording medium according to the present invention
  • Figure 19 is a cross-section of a magnetic recording medium according to the present invention in which the soft magnetic underlies the nonmagnetic layer and the magnetic recording layer;
  • Figure 20 illustrates a schematic representation of the two-dimensional computer model used to study the interaction of the TF head with a magnetic recording medium having a soft magnetic layer underlying the magnetic recording layer according to the present invention
  • Figures 21 and 2IB illustrate magnified views of the magnetic exchange coupling between the TF head and a
  • a magnetic recording medium having enhanced magnetic recording characteristics and capable of producing improved signal quality, especially with respect to noise and strength. As a result, higher data densities may be achieved by maintaining a useful signal level. Need for expensive drive electronics to improve overall signal quality is reduced as well. Furthermore, the magnetic recording medium of the present invention can cooperate with advanced electronics to greatly extend data storage capacities.
  • the '922 patent discloses a magnetic recording medium having a substrate 12 and a magnetic recording layer 16 in direct contact with a soft magnetic layer 18 as shown in Figure 1 and referred to here as the "direct contact" structure 10.
  • the structure reportedly has improved signal strength at high frequencies and reduced spacing and reproduce gap losses, attributable to direct contact between the magnetic recording layer and the soft magnetic layer.
  • Figure 2 taken from the related technical paper, shows the reported improvement in output signal at higher data densities in a magnetic recording medium where a saturating bias is applied to the "direct contact" structure.
  • a gap null is apparent at about 70 kfci.
  • the present invention obtained reproducible enhanced magnetic recording performance over that described in the '922 patent by interposition of a nonmagnetic "break" layer between the soft magnetic layer and the magnetic recording layer.
  • This configuration referred to as a "break layer” configuration 30, is illustrated in Figure 4.
  • a magnetic recording layer 16 overlies the substrate 12 and an optional though preferred nucleating layer 14 and a nonmagnetic layer 22 lies between the magnetic recording layer 16 and a soft magnetic layer 18.
  • a protective layer 20 of a material such as carbon overlies the soft magnetic layer.
  • Figure 5 compares the frequency responses for the break layer configuration 30 in the uppermost curve and a conventional magnetic recording disk in the lowermost curve.
  • the uppermost curve shows a substantial gain in output signal compared to the lowermost curve across the full density range. Further, useful gain in signal is observed across a range of data densities from 1 kfci up to 70 kfci or more. Usable signal strength may be obtained even at higher data densities because of reduced spacing losses and gap length reduction, as described in detail below.
  • the curves in Figure 6 illustrate, at high resolution over shorter band width, the reduction in finite pole effects.
  • the uppermost curve (for the break layer configuration 30) is smooth and lacks any significant head bumps in the frequency range studied.
  • the lowermost curve (for the conventional magnetic recording medium) shows several head bumps, reducing the output signal at about 22 kfci, 35 kfci, 48 kfci and 60 kfci.
  • Figure 7 illustrates graphically the substantial reduction in overall spacing loss, i.e., read and write spacing losses combined, achieved over a wide range of head flying heights, d, by a magnetic recording medium incorporating break layer configuration 30 as compared with a conventional magnetic recording medium.
  • the signals were recorded with a wavelength ( ⁇ ) of 28.5 microinche ⁇ .
  • Figures 8 and 9 compare qualitatively the signal-to- noise ratio (SNR) obtained from the break layer configuration 30 with that from the conventional magnetic recording disk, respectively.
  • SNR signal-to- noise ratio
  • Figures 10 and 11 illustrate the improved bit shift data obtained for the magnetic recording media of the present invention as compared with that from the conventional magnetic recording medium, respectively. Specifically, a comparison of the curves shows that with a magnetic recording medium incorporating the break layer configuration 30, a soft error rate of 1 bit in 10 9 bits at which a bit shift of 10 nanoseconds (nsec) can be maintained even at data densities of 50 kfci. In a conventional magnetic recording medium at such a data density, the bit shift increases to a significantly higher 13.3 nsec.
  • Figures 12 and 13 illustrate the pulse width at 50% of maximum height, PW50, of isolated signal pulses read from the conventional magnetic recording medium and the break layer configuration 30, respectively.
  • the PW50 is about 72 nsec. Some asymmetries, head bumps and other noises such as "wiggle" appear in the "shoulders" of the signal.
  • the break layer configuration 30 a significantly narrower and cleaner signal is observed. PW50 is reduced to about 55 nsec and the signal shows neither head bumps nor asymmetries, and virtually no noise in the wings. From these cumulative results, it unexpectedly appears that with the break layer configuration 30, data densities could be increased by about a factor of 2.
  • the observed improvements in magnetic recording properties are due to the interruption of effects of magnetic exchange coupling that results from the interposition of the break layer between the magnetic recording layer and the soft magnetic layer.
  • the break layer interrupts the magnetic- exchange coupling between the soft magnetic layer and the magnetic recording layer, allowing the latter two layers to react separately to the flux induced by the bias current in the head.
  • Figure 14 illustrates schematically a two- dimensional computer model used to study the reduction in spacing losses resulting upon application of a bias current to a medium having a soft magnetic layer M and break layer overlying the magnetic recording layer and being scanned by a conventional TF head 40 with the intent to read bit 49.
  • Spacing losses are qualitatively indicated by the changes in the coupling of magnetic flux from the given bit through an equivalent magnetic reluctance representing the presence and operation of the schematically shown head core 45 upon application of a small (about 1 milliamp) DC bias current, I B .
  • the resultant signals would be detected as voltages, V s .
  • Additional parameters of the model were as follows: poles 42A, 42B of head 40 separated by a 0.44 micron gap with a head flying height d of 5 microinch.es.
  • Figures 15A and 15B illustrate on magnified scales the interaction of a TF head 40 with a conventional magnetic recording medium, during the playback or read operation.
  • Flux lines 44, 46, 48 from surrounding bits 50, 52 couple with the head poles 42A and 42B, with flux from these bits coupling through the equivalent magnetic reluctance of the head core 45 interconnecting the poles.
  • Other flux lines 54, 56 emerge from adjacent bits 50, 52, also coupling through the equivalent magnetic reluctance.
  • the output signal detected by the head is a product of the flux from more than one bit.
  • Figures 16A and 16B illustrate on magnified scales the interaction of the head 40 with a magnetic recording medium incorporating the break layer configuration 30.
  • the magnetic recording medium consisted of a substrate, a 775A magnetic recording layer, a 100A carbon break layer, a 700A keeper layer and a 250A carbon protective layer.
  • flux lines 56, 58 otherwise retained by the keeper layer above the bit 49, 'leak' along the keeper layer toward the head.
  • Flux from all other bits 50, 52 remains keepered, as indicated by flux lines 57, 59.
  • Figures 17 and 18 are the BH loops of a conventional horizontal magnetic recording medium and of the break layer configuration 30, respectively.
  • Figure 17 depicts a loop of typical configuration, indicating that the medium switches smoothly throughout the cycle of polarity changes in the applied magnetic field.
  • the shape of the BH loop in Figure 18 contrasts sharply.
  • the height of the BH loops differs, with the total height of the BH loop (i.e., dimension along the B axis) dependent on the sum of the moments of the soft magnetic and magnetic recording layers.
  • the observed discontinuities or "bumps" in the BH loop suggest that magnetization of the NiFe layer 18 and the magnetic layer 16 switch independently. It is submitted that the discontinuities manifest a break of the magnetic exchange coupling between the soft magnetic layer and the magnetic recording layer.
  • the location of the bumps indicates the relative proportions of the soft magnetic material and magnetic recording material in a magnetic recording medium incorporating the break layer configuration.
  • substrate 12 is a nickel-phosphorus-plated aluminum disk used in Winchester-type hard disk drive technology. Nonmetallic substrates such as glass, carbon and ceramic materials also may be suitable. The disk surface may require cleaning or other treatments to enhance adhesion of the subsequently deposited layer. In addition, surface treatments such as texturizing or polishing are known to promote a desired crystalline morphology in the subsequently deposited magnetic recording layer.
  • substrate 12 may be a tape suitable for conventional magnetic tape- recording, e.g., polyvinylidene chloride, or a sheet of thermoplastic material, such as polyethyleneterephthalate, suitable for use in conventional floppy disks. Other surface treatments may be employed to prepare the latter substrates for subsequent deposition.
  • the magnetic recording layer 16 may be formed from any of a variety of magnetic compositions useful as horizontal and vertical recording materials, as is well known in the art.
  • the thickness of the magnetic recording layer 16 can range from 20 ⁇ A to lOOOA, with 30 ⁇ A to 70 ⁇ A being most preferred.
  • Polycrystalline magnetic recording materials may require deposition of a nucleating layer 14.beneath the magnetic recording layer 16 to help promote the desired morphology and crystalline growth and therefore magnetic properties in the magnetic recording layer 16.
  • a nucleating layer 14 applied between the substrate 12 and magnetic layer 16 may be necessary to help establish the desired hexagonal close packed (hep) growth necessary in the CoCr or CoNi magnetic recording layer 16.
  • the nucleating layer thickness is preferably between about lOoA and about 2000A, with the most preferred thickness between about 20 ⁇ A and about IOOOA.
  • the nonmagnetic layer 22 may be formed from a wide variety of nonmagnetic materials that are immiscible with the magnetic recording and soft magnetic layers and do not upset crystal structure of the adjacent magnetic layers.
  • nonmagnetic materials include metals such as chromium, molybdenum and tungsten, metalloids such as carbon, silicon and germanium, titanium and alloys of these elements, glasses, alumina and other refractory materials, elastomeric materials such as those sold under the trade name PARALENETM and even lacquer-like materials.
  • Preferred nonmagnetic break layer materials are chromium, carbon and silicon, with the latter being most preferred.
  • the crystalline morphology of the nonmagnetic break layer material may be an important consideration in its selection, since its morphology may influence epitaxy and therefore, magnetic properties of subsequently deposited layers. As a consequence, introduction of additional nonmagnetic layers between the magnetic recording layer and the soft magnetic layer to effect a particular crystalline morphology in either the soft magnetic layer or the magnetic recording layer is considered to be within the scope of the present invention.
  • the thickness of the nonmagnetic break layer should be sufficient to interrupt magnetic exchange coupling between the magnetic recording layer and the soft magnetic layer. However, it is desirable that the thickness of the nonmagnetic layer be sufficiently thin so as to avoid interference with the flux-induced signal, e.g., by contributing to additional spacing losses during the write process. Therefore, generally, only a thin layer is necessary to achieve this effect, with a thickness of between about 15A to about 300A being adequate. Thicknesses between about 25A and about 150A are preferred. However, in some instances, a thin layer, approximating the thickness of a monolayer, sufficient to fully interrupt the magnetic exchange coupling between the magnetic recording layer and the soft magnetic layer, may be used.
  • the soft magnetic layer 18 may be formed from a wide variety of soft magnetic materials well known in the art of drive head manufacture, including pure Ni, Fe, or Co, or their alloys including NiFe (sold under the trade name PERMALLOYTM), or aluminum-iron-silicon (AlFeSi, sold under the trade name SENDUSTTM), cobalt-zirconium-niobium (CoZrNb), and other alloys.
  • the soft magnetic material is corrosion-resistant.
  • Other materials which may be suitable for use as the soft magnetic layer are amorphous alloys or polycrystalline materials having near zero magnetostriction.
  • the thickness of the soft magnetic layer should be sufficient to retain or keeper all of the flux from the data recorded in the magnetic recording layer. This effect may. be achieved by a layer of a single soft magnetic material or a lamination of several layers of one or more soft magnetic materials separated by thin nonmagnetic break layers.
  • the actual thickness necessary is a function of the moment of the material used as the soft magnetic layer.
  • a soft magnetic layer 18 composed of NiFe may be between about 700A and about 1200A. Most preferred is a thickness about 75 ⁇ A.
  • a thickness of about 35 ⁇ A is adequate, as predicted based upon the moment for CoZrNb being about twice that of NiFe.
  • break layer configuration 30 is illustrated with the soft magnetic layer 18 overlying the magnetic recording layer 16, the opposite configuration is contemplated as within the scope of the present invention. That is, a break layer configuration 60, as shown in Figure 19, may be prepared with the soft magnetic layer 18 being deposited directly on the substrate 12 and nucleating layer 14, followed by the nonmagnetic layer 22 and then the magnetic recording layer 16.
  • Figure 20 illustrates schematically the two- dimensional computer model for a magnetic recording medium incorporating break layer configuration 60.
  • the soft magnetic layer M lies underneath the magnetic recording layer where bits 49, 50 and 52 are located.
  • the nonmagnetic break layer 22 separates the soft magnetic layer from the magnetic recording layer. Otherwise, the model parameters are identical to those described in connection with Figure 14.
  • the model predicts that such a medium can achieve improvements in magnetic flux coupling and head efficiency of at least comparable magnitudes to those observed for the medium incorporating break layer configuration 30 in which the soft magnetic layer .overlies the magnetic recording layer.
  • Figures 21A and 2IB illustrate on magnified scales the interaction of the TF head 40 with the medium during the read operation.
  • the protective outer layer 20 protects the magnetic recording medium according to the present invention from wear and the corrosive effects of any vapors present within the magnetic signal processing device.
  • the protective outer layer 20 may be composed of metals including rhodium, or nonmetallic materials such as carbon and inorganic non-metallic carbides, nitrides and oxides, e.g., silica or alumina.
  • the thickness may be between about 20 ⁇ A and about 35 ⁇ A; a carbon thickness between about 225A and about 35 ⁇ A is most preferred.
  • a magnetic recording medium having the break layer configuration 30 is prepared by the sequential deposition of the layers onto the substrate 12.
  • a preferred configuration employs a 40 ⁇ A Cr underlayer 14, a 500A cobalt- ⁇ hromium-tantalum (CoCrTa) layer 16, a 25A carbon break layer 22, a 70 ⁇ A NiFe layer 18 and a 30 ⁇ A protective carbon layer 20.
  • An alternate preferred configuration employs a 40 ⁇ A Cr underlayer 14, a 50 ⁇ A CoCrTa layer 16, a 25A silicon break layer, a 40 ⁇ A CoZrNb layer 18 and a 30 ⁇ A protective carbon layer 20.
  • Deposition of the various layers may be achieved according to means well-known in the art, for example, by sputtering, plating, evaporation or other thin film deposition methods, alone or in combination.
  • Other means more exotic relative to conventional magnetic recording disk manufacturing processes, such as chemical oxidation, coating, spinning, baking or polymerization, may . also be used to deposit the desired thin films, particularly those methods that are adaptable to nonmetallic materials.
  • a key factor in achieving the structure described in the present invention is maintenance of the integrity of the magnetic recording layer 16 until the subsequent deposition of the nonmagnetic layer 18.
  • film integrity is quite easily maintained by virtue of an evacuated environment within the apparatus that minimizes oxidation and contamination of each layer until a subsequent layer is deposited.
  • the multilayer configuration of the media of the present invention was produced in an in-line DC magnetron sputtering process and apparatus, such as those described in co-pending Application Serial No. 07/681,866, incorporated herein by reference, where interlayer integrity may be easily maintained in the highly evacuated multiple chamber sputtering apparatus.
  • deposition parameters may be selected to optimize film properties such as thickness and morphology to tailor the magnetic properties of the magnetic recording medium prepared.
  • relatively low sputtering pressure about 2 microns argon
  • bias current As discussed earlier, application of only a small bias current is necessary to saturate the soft magnetic layer in the region of the bit to be read.
  • the actual current applied may vary with the TF head used, its efficiency, and the thickness of the soft magnetic layer in the magnetic recording medium.
  • the bias current need be only of a magnitude that is sufficient to achieve saturation and typically ranges between about 0.5 milliamps (mA) to about 1.5 mA.
  • Such a current may be either AC or DC, though preferably is DC.
  • the magnetic recording media of the present invention improves magnetic recording properties by provision of a relatively thinner nonmagnetic layer interposed between a soft magnetic layer and a thin magnetic recording layer. Overall signal strength and quality are increased even at substantially higher data densities than are achievable with conventional magnetic recording media.
  • a wide variety of conventional materials and fabrication techniques may be used to prepare the novel magnetic recording media of the present invention.

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  • Inorganic Chemistry (AREA)
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Abstract

On décrit un support d'enregistrement magnétique comportant une couche mince de matériau non magnétique (22) séparant une couche magnétique douce (18) et une couche d'enregistrement magnétique relativement plus épaisse (16). Le support d'enregistrement magnétique peut comporter des matériaux d'enregistrement magnétiques conventionnels associés à la couche mince non magnétique (22) en silicium, chrome ou carbone. Le support d'enregistrement magnétique peut être préparé par pulvérisation cathodique ou autres procédés de dépôt en phase vapeur. Un procédé de préparation d'un support d'enregistrement magnétique, selon la présente invention, propose de déposer la couche (16) d'enregistrement magnétique soit directement sur un substrat (12), soit, éventuellement, sur une couche de nucléation (16). La couche non magnétique mince (22) sépare la couche d'enregistrement magnétique (16) de la couche magnétique douce (18). Le dépôt est réalisé dans des conditions qui maintiennent l'intégrité de la couche d'enregistrement magnétique.
PCT/US1992/010485 1992-01-03 1992-12-07 Supports d'enregistrement magnetiques comportant un materiau magnetique doux WO1993012928A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP5511674A JPH07503337A (ja) 1992-01-03 1992-12-07 軟磁性材料を用いた磁気記録媒体
EP19930900873 EP0619776A4 (fr) 1992-01-03 1992-12-07 Supports d'enregistrement magnetiques comportant un materiau magnetique doux.

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JPH08204253A (ja) * 1995-01-27 1996-08-09 Nec Corp 磁気抵抗効果膜
WO1996025734A1 (fr) * 1995-02-15 1996-08-22 Velocidata, Inc. Systeme de reproduction d'enregistrement magnetique utilisant une derivation d'entrefer a reluctance variable
EP0780834A2 (fr) 1995-12-20 1997-06-25 Ampex Corporation Tête magnétique de lecture/écriture à deux entrefers
EP0780833A2 (fr) 1995-12-20 1997-06-25 Ampex Corporation Système d'enregistrement magnétique amélioré à couche saturable et détection utilisant un élément MR
EP0817173A1 (fr) * 1996-06-28 1998-01-07 Ampex Corporation Système d'enregistrement et de reproduction magnétique avec une couche de fermeture à perméabilité basse et une tête de reproduction magnéto-résistive auto-polarisée
WO1998006094A1 (fr) * 1996-08-06 1998-02-12 Ampex Corporation Procede et appareil pour enregistrement magnetique et supports de lecture dotes d'une couche a effet de pont magnetique presentant une anisotropie longitudinale
EP1298648A1 (fr) * 2001-09-07 2003-04-02 Fujitsu Limited Support d'enregistrement magnétique et dispositif de stockage magnétique
US6815097B2 (en) 1999-01-29 2004-11-09 Showa Denko K.K. Magnetic recording medium
US6841259B1 (en) * 2000-05-31 2005-01-11 Migaku Takahashi Magnetic thin film, production method therefor, evaluation method therefor and magnetic head using it, magnetic recording device and magnetic device
US7425377B2 (en) * 2005-02-04 2008-09-16 Hitachi Global Storage Technologies Netherlands B.V. Incoherently-reversing magnetic laminate with exchange coupled ferromagnetic layers
US7989096B2 (en) 2005-02-04 2011-08-02 Hitachi Global Storage Technologies Netherlands B.V. Perpendicular recording media having an exchange-spring structure
US7988061B2 (en) 1999-10-23 2011-08-02 Ultracard, Inc. Article having an embedded accessible storage member, apparatus and method for using same
EP1224664B1 (fr) * 1999-10-23 2013-01-09 Ultracard, Inc. Dispositif de stockage de données, appareil et méthode pour son utilisation
US9430727B2 (en) 1999-10-23 2016-08-30 Ultracard, Inc. Data storage device, apparatus and method for using same

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US5041922A (en) * 1985-12-13 1991-08-20 Ampex Corporation Magnetic recording medium having magnetic storage and saturable layers, and apparatus and method using the medium
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US5041922A (en) * 1985-12-13 1991-08-20 Ampex Corporation Magnetic recording medium having magnetic storage and saturable layers, and apparatus and method using the medium
US5147732A (en) * 1988-09-28 1992-09-15 Hitachi, Ltd. Longitudinal magnetic recording media and magnetic memory units

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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08204253A (ja) * 1995-01-27 1996-08-09 Nec Corp 磁気抵抗効果膜
WO1996025734A1 (fr) * 1995-02-15 1996-08-22 Velocidata, Inc. Systeme de reproduction d'enregistrement magnetique utilisant une derivation d'entrefer a reluctance variable
US5729413A (en) * 1995-12-20 1998-03-17 Ampex Corporation Two-gap magnetic read/write head
EP0780833A2 (fr) 1995-12-20 1997-06-25 Ampex Corporation Système d'enregistrement magnétique amélioré à couche saturable et détection utilisant un élément MR
EP0780833A3 (fr) * 1995-12-20 1999-01-07 Ampex Corporation Système d'enregistrement magnétique amélioré à couche saturable et détection utilisant un élément MR
US5870260A (en) * 1995-12-20 1999-02-09 Ampex Corporation Magnetic recording system having a saturable layer and detection using MR element
EP0780834A2 (fr) 1995-12-20 1997-06-25 Ampex Corporation Tête magnétique de lecture/écriture à deux entrefers
EP0817173A1 (fr) * 1996-06-28 1998-01-07 Ampex Corporation Système d'enregistrement et de reproduction magnétique avec une couche de fermeture à perméabilité basse et une tête de reproduction magnéto-résistive auto-polarisée
WO1998006094A1 (fr) * 1996-08-06 1998-02-12 Ampex Corporation Procede et appareil pour enregistrement magnetique et supports de lecture dotes d'une couche a effet de pont magnetique presentant une anisotropie longitudinale
US5861220A (en) * 1996-08-06 1999-01-19 Ampex Corporation Method and apparatus for providing a magnetic storage and reproducing media with a keeper layer having a longitudinal anisotropy
US6815097B2 (en) 1999-01-29 2004-11-09 Showa Denko K.K. Magnetic recording medium
US7988061B2 (en) 1999-10-23 2011-08-02 Ultracard, Inc. Article having an embedded accessible storage member, apparatus and method for using same
US9430727B2 (en) 1999-10-23 2016-08-30 Ultracard, Inc. Data storage device, apparatus and method for using same
EP1224664B1 (fr) * 1999-10-23 2013-01-09 Ultracard, Inc. Dispositif de stockage de données, appareil et méthode pour son utilisation
US6841259B1 (en) * 2000-05-31 2005-01-11 Migaku Takahashi Magnetic thin film, production method therefor, evaluation method therefor and magnetic head using it, magnetic recording device and magnetic device
EP1298648A1 (fr) * 2001-09-07 2003-04-02 Fujitsu Limited Support d'enregistrement magnétique et dispositif de stockage magnétique
US7327528B2 (en) 2001-09-07 2008-02-05 Fujitsu Limited Magnetic recording medium and magnetic storage apparatus
US7232620B2 (en) 2001-09-07 2007-06-19 Fujitsu Limited Magnetic recording medium and magnetic storage apparatus
EP1619672A1 (fr) * 2001-09-07 2006-01-25 Fujitsu Limited Support d'enregistrement magnétique et dispositif de stockage magnétique
US6670057B2 (en) 2001-09-07 2003-12-30 Fujitsu Limited Magnetic recording medium and magnetic storage apparatus
US7425377B2 (en) * 2005-02-04 2008-09-16 Hitachi Global Storage Technologies Netherlands B.V. Incoherently-reversing magnetic laminate with exchange coupled ferromagnetic layers
US7989096B2 (en) 2005-02-04 2011-08-02 Hitachi Global Storage Technologies Netherlands B.V. Perpendicular recording media having an exchange-spring structure

Also Published As

Publication number Publication date
EP0619776A4 (fr) 1994-12-07
JPH07503337A (ja) 1995-04-06
EP0619776A1 (fr) 1994-10-19

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