Dual Track Complimentary (DTC) type of recording head suitable for perpendicular magnetic recording system has been presented in this study in order to attain higher efficiency in read/write process. Two dimensional analysis of DTC head using conformal mapping technique implied that DTC configuration of head is suitable for the perpendicular magnetic recording system because of its strong magnetic field normal to the media plane in the region between the head tips and the backlayer of the recording media. Recording characteristics using a 90° rotated conventional type of ring head and Ba-ferrite particulate floppy disk media was evaluated. The results implied that the recording principle using DTC configuration were applicable to the perpendicular recording system. Thin film type of DTC head was prepared using photolithography technique. The head composed of Co-Zr amorphous core layers and Al wiring layer has relatively low inductance as low as about 0.2 μH.

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  The shaping of the pole tip configuration of inductive thin film heads, at the air bearing surface by ion milling, is thought to be one of the promising technologies to boost the areal density of the disk drives. It was found to realize the undershoot suppression of the isolated readback waveform, which enables the heads to adapt to the PRML read/write channel processing easier. Further, the off-track capability was also found to be improved by truing up the track side edges of both upper and lower poles.
  The latter was achieved by trimming both sides of the upper and lower pole tips of inductive thin film heads to become nearly the same in width, through photolithography and ion milling processes at the air bearing surface. The off-track capability enhancement attained by the pole trimming was experimentally estimated by performing off-track profile evaluation and "747 curve" measurement. The difference between the effective track width and the upper pole width (ETW-P2W), which represents the amount of the effect of track side writing and side crosstalk, was found to be reduced to 68% of that seen in conventional thin film heads. It was also found that the track interval can be squeezed by as much as 1.0 μm more than conventional thin film heads, based on the 747 curve comparison.

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  In this paper, it is discussed that the pole recession in the perpendicular thin film magnetic head has been influenced by means of lapping and polishing.
  Although the pole recession is not improved by the diamond polishing process, it was found that MCP (Mechano-Chemical-Polishing) method gave a good result on decreasing the recession. Polishing rate of composed materials are changed by the pH of a solution in MCP and the pole recession can be decreased to minimize by controlling the pH and machining time of MCP process.

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  The effects of thermal transients after write, changes in stress-magnetostriction products and dynamic domain instabilities on popcorn noise probabilities in micro Flexhead^® components were studied. It was observed that popcorn noise probabilities in micro Flexhead^® components increase as the write current duration increases, until they saturate, with a specific write current amplitude. With increasing write current amplitude, the initial rate of change of noise probability with write current duration increases. In some cases where the resultant stress-magnetostriction products in micro Flexhead^® components are negative, popcorn noise probabilities were observed to increase exponentially as functions of applied stress gradients. High rates of occurrence of dynamic domain instabilities have also been correlated with micro Flexhead^® components that have high popcorn noise probabilities. Therefore, high probabilities of popcorn noise in micro Flexhead^® components are caused by the combined effects of thermal transients after write, changes in stress-magnetostriction products and dynamic domain instabilities. Finally, an inductance fluctuation measurement technique was shown to be useful in quickly detecting micro Flexhead^® components that are susceptible to popcorn noise.

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  A thin film magnetic head has been expected to be applied to high density recordings. However, the practical use of the head for video recordings is not yet realized because of its problems regarding head contact reliability, impedance noise and low frequency transmission characteristics. In order to overcome such problems, authors have developed a new thin film magnetic head for video recording applications, which is made solely of high heat resistant inorganic materials, the coil resistance of which is lowered. The developed head is evaluated by using a metal evaporated tape (ME tape) and a metal particulate tape (MP tape). The head of innovative structure is proved to be highly reliable both in the normal and level-different wear characteristics, and to have a superior low frequency transmission characteristic and a high carrier-to-noise ratio. And having a gap depth of 5μm, the newly developed head has sufficient performance for VCR.

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  We have investigated a thin film head for VCR application whose shape looks like a conventional ring head. Its structure is able to make a short magnetic circuit and a long gap depth. The coil is winded helicoid onto the core three-dimensionally by thin film processing technique. We made a test device with a core using a Sendust film which is well known as a material of high maximum magnetic flux density and high permeability. The playback output of this thin film head having a Sendust core is smaller than that of a CoZr based amorphous core. Characteristics of the core material such as permeability and hardness is very important for the thin film head.

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  A new silicon integrated magnetic head with a very narrow track width has been achieved. A collective process has been used to carry out a vertical gap fabrication which avoids a glass bonding in the gap area, and allows an integrated coil elaboration. Wear behaviour and frequency dependance for reproduced output level have been investigated.

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  The switching field and the coercivity field of the Stoner-Wohlfarth particles though defined differently is nearly equal to each other in magnitude whenever the corresponding hysteresis loop is fairly rectangular in shape. As the result of large inclination in the field angle, thermal relaxation and textural distribution effects, however, the hysteresis loop may become strongly sheared and the side of the loop dips below zero before the switching taking place so they begin to deviate from each other appreciably.

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  Acicular barium ferrite particles have been prepared by a conventional sintering method. Then, the mixture of these particles and binder resins was coated on the polyester film under a magnetic field of 7 kÖe being applied normal to the surface of the film. The magnetic torque curve of the coated film has been noted that the axis of easy magnetization of the film was perpendicular to the film. In addition, the crystal structure of a simple body of acicular barium ferrite particle was investigated by the selected-area electron diffraction pattern. It was obtained that the c-axis of hexagonal barium ferrite was normal to the long axis of an acicular particle. Moreover, the acicular particle consisted of some hexagonal grains, and the a-axis of them had fluctuations with a small angle.

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  The temperature dependence of the magnetic viscosity coefficient Sv and average anisotropy field H_A(ave) were examined for Ba-ferrite fine particles having mean particle volume V of 3.2 × 10^-17 cm³, in the temperature range from 200 to 413K. A study was done for the relationship between the activation volume ν calculated based on Sv and average anisotropy constant K_A(ave) for Ba-ferrite fine particles. This experiment showed that the temperature dependence of Sv is the same as that of coercive force Hc, and Sv increases with the increase of the temperature. H_A(ave) linearly increases as the temperature increases in the temperature range from 293 to 413 K. The activation volume ν is inversely proportional to K_A(ave). The values of ν and the critical volume Vc for superparamagnetic behaviour at 293K, are approximately 1.35 × 10^-17 and 0.23 × 10^-17 cm³, respectively. Larger K_A(ave) value is necessary for smaller ν value which is an important factor for high-density magnetic recording. Also, the relations V/ν › 1 and V/Vc ›› 1 are of significant importance.

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  Although the particulate magnetic recording industry is mature, there still remains an unsolved problem of dispersion quality which plagues any coating process involving unstable particle suspensions. We examine this issue in light of three different characterization techniques: rheomagnetic, rheooptic, and rheological measurements. We use these techniques to study the dispersion state of various single domain magnetic particles (rod-like γ-Fe₂O₃ or CrO₂ and plate-like Ba-Ferrite). Theory is also developed to interpret data and provide a unified description of characterization of dispersion quality.

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  I. Tagawa-Y. Nakamura's parameter ΔHc/Hc of the switching field distribution(SFD) has been measured on metal Fe and CrO₂ particulate coatings made from various degrees of dispersion to evaluate the dispersion quality and particle orientability in paints by magnetic measurements. The parameter ΔHc/Hc has been shown to correlate with the gloss and SQR used to estimate the dispersion quality and the orientaion degree until now. The parameter ΔHc/Hc and ΔHc/Hc-SQR plots indicate effective tools to evaluate the particle dispersion and orientability in paints and coatings.

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  Measurement of interaction effects in magnetic recording media using techniques based on the Wohlfarth relation are reviewed. An extension of the technique to describe combined forward and reverse magnetisation from any initial starting condition is described. This is applied to samples of recording media and families of equivalent Henkel plots are produced for a series of partially DC-demagnetised starting states.

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  Surface spin waves in CoPt alloy films with perpendicular c-axis orientation of hcp-Co have been studied by Brillouin light scattering for the high-density magnetic recording. The spin-wave energy depends on the Pt-content, which is explained by the change of the perpendicular magnetic anisotropy, as well as the saturation magnetization. From the dependence of the spin-wave energy on the magnetic field, magnetic constants are derived, such as g-value and uniaxial anisotropy constant. Line broadening of the spin-wave Brillouin spectra are also discussed.

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  Quantitative characterizations of magnetic anisotropy of grains and intergranular coupling were carried out in (Co₈₆Cr₁₂Ta₂)_100-XPt_X (X=1∼9) and (Co_62.5Ni₃₀Cr_7.5)_100-XPt_X (X=0∼16) thin film media, by magnetic torque and ΔM analyses. In both materials, magnetocrystalline anisotropy field of grains H_k^grain increases twice as large as those of X=0 with increasing X to about 9at%, which plays a main role in increasing H_c. However, H_c/H_k^grain decreases with increasing X in both media. In CoCrTaPt media, the decrement of H_c/H_k^grain is found to be mainly caused by the increment of intergranular exchange coupling. In CoNiCrPt media, it is suggested that the change of c-axes directions from in plane to normal mainly causes the decrement in H_c/H_k^grain. Furthermore, to examine the effect of intergranular coupling on magnetic properties by means of ΔM plot, it is clarified that the difference of H_k^grain should be taken into account.

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  We have observed very unusual hysteresis loops with a "negative coercivity" in our VSM measurement for a film sample in perpendicular direction. It was found that the phenomenon could become a problem in the perpendicular hysteresis loop measurement for composite perpendicular recording media with a high permeable backlayer. It was determined that the origin of this fictitious hysteresis curve is parasitic signal caused by a vertical moment in the sample accompanied with a lateral vibration. Although the intrinsic reduction of the lateral vibration is essential to reduce the parasitic signal it was found that an intended small angle deviation of the sample is effective.

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  The environmental stability of various types of magnetic metal particle and metal thin film types were studied and compared with respect to both media types as well as substrate. The present work was focused on commercially available media of both MP (metal particle) and ME (metal evaporated) type on PET and Mictron^TM substrates. The studies discussed herein include evaluation of the loss in saturation and remanent magnetic moments as a function of accelerated aging at elevated temperature and humidity (65°C and 85% RH). The results of a limited study on chemical corrosion (Battelle type) on advanced MP tapes are also reported. We found significantly greater corrosion in some advanced MP media utilizing smaller metal particles with larger specific surface areas. We also found much greater corrosion in ME media deposited on p-aramid substrates which contain chlorine.

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  The height and lateral width of the magnetic domains and the mean orientation of the domain magnetisation in a two-layer Co₈₀Ni₂₀ metal-evaporated tape are determined by angular dependent neutron depolarisation. It appears that the magnetic domains are not homogeneously magnetised, but consist of magnetic grains with a magnetisation that is higher than the mean magnetisation of the domains. The correlation length of these grains is found to be 10nm. The measured orientation of the domain magnetisation in each layer is 44°, the domain width is equal to the domain height.

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  Measurements of the structural, magnetic, and recording properties of several commercial metal evaporated (ME) tapes are presented. Special attention is paid to the effect of multiple layers, with different easy-axis directions, on these properties. We find evidence that the different layers in ME tape are magnetically independent from one another.

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  This paper discusses the effect of an increase in layer thickness (from 40 nm to 1.7 μm) and an increase in deposition rate (from 0.5 to 20 nms^-1) on the structure and magnetic properties of Co₈₀Ni₂₀ thin films deposited at incidence angles between 70° and 80° (with respect to the substrate normal). The coercivity and anisotropy increase and the anisotropy in electric resistance decreases with increasing layer thickness up to a thickness of 150 nm. In all samples strong stripe domain structures were observed. The equilibrium domain period increases with increasing layer thickness. An increase in rate of evaporation from 0.5 to 20 nms^-1 increases coercivity and anisotropy.

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  A mini-rollcoater deposition system has been built in order to prepare metal evaporated tapes. The deposition rate of the Co₈₀Ni₂₀ was varied. It appears that the value of the coercivity can partly be explained by considering the effect of oxidation on the diffusion processes. The inclination of the columns depends on the deposition rate and the oxygen supply. Low temperature hystereses showed a large ferromagnetic-antiferromagnetic coupling effect. Recording experiments show that a high coercivity is necessary for acceptable output at high frequencies; intrinsic domains are suggested to limit the smallest recordable wavelength.

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  Diamond like carbon(DLC) film were deposited on Co-O magnetic layer with protrusions. The role of DLC film for ME tape reliability was investigated and compared with conventional ME tape in the running and still mode of Hi-8 VTRs. DLC film were inactive to transport system materials of VTR and had passivation capability even for thicknesses of only 10nm. By applying DLC film for ME tape, we can realize advanced ME tape with minimum head-to-tape spacing and head wear, and with superior durability and archivability.

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  The authors have examined magnetization 4πMs, magnetic anisotropy K₁, and coercivity H_c, for a series of single crystal MnZn-ferrite films pulsed laser ablated in oxygen pressures of 15, 30, 60 and 90 milli-Torr. The results show that K₁, 4πM_s and H_c are very sensitive to the oxygen partial pressure. Depending on the deposition temperature and oxygen pressure, 4πM_s can in some instances have values approximately three times the bulk value of 4,000 Gauss. The magnetic properties appear to be optimum for oxygen pressures between 30 and 60 milli-Torr.

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  Films of Mn, Ni and Ba-containing iron oxides are successfully synthesized from chelated highly-alkaline aqueous solution by ferrite plating method on substrates heated by Xe-lamp beams. The solubility limits of Mn and Ba are Mn/Fe=∼0.3 and Ba/Fe=∼0.16, respectively, which are much higher than that obtained by conventional ferrite plating using neutral aqueous solution. When Ba/Fe>›∼0.06, the films do not exhibit the X-ray scattering peaks due to crystalline structure. After annealing the Ba-containing iron oxide films (Ba/Fe=∼0.1), the X-ray scattering peaks due to BaFe₁₂O₁₉ crystalline phase appeared. The films as synthesized are small in grain size (‹∼100 nm), having no columnar structure as observed by SEM.

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  Ni-and NiZn-ferrite films were synthesized at 90°C on Au film substrate from an aqueous solution by conducting alternate current (V_p-p=8.4 V, f=10∼1000Hz) between the substrate and a Pt electrode. The chemical composition x in Ni_xFe_3-xO₄ and x+y in Ni_xZn_yFe_3-x-yO₄ reaches ∼0.6 and ∼0.9, respectively, which increased much as compared to those obtained by conventional ferrite plating utilizing no electric current. The deposition rate of the films decreased from ∼20 to ∼5∼10 nm/min as the frequency increased from 10 Hz to 1000 Hz. All the films were polycrystalline with no preferential orientation, and the magnetization lay in the film plane. The dependence of the saturation magnetization on chemical composition agrees with that observed for bulk samples.

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  Ba-ferrite films depending on the parameters of composition of Fe/Ba ratio, substrate temperatures (T_s) and post-annealing temperatures (T_a) were fabricated. C-axis of high iron concentration film (Fe/Ba=15.3) was well-oriented normal to the film surface, when the film was annealed at T_a=900°C after deposited at T_s=750°C. The film had large magnetic anisotropy (K_u=8.04×10⁵ erg/cc) in the direction normal to the film. It appeared that the films with perpendicular anisotropy were obtained by the existence of (111)Fe_xO in the as-deposited film and by the formation of solid solution of a spinel-type compound like Fe₃O₄ in the hexagonal structure.

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  Excellent c-axis perpendicularly oriented barium hexaferrite thin films have been achieved on both (111) and (100) Pt underlayers by either conventional rf diode or magnetron sputtering. TEM cross section study has revealed a sharp interface between the barium hexaferrite and the Pt underlayer, indicating no extensive interfacial reactions between layers. This has enabled fabrication of very thin barium hexaferrite films as thin as 50Å. A 50Å thick Pt underlayer is sufficient to produce a good c-axis perpendicular orientation in the barium hexaferrite layer. High coercivity (above 2000 Oe) perpendicular barium hexaferrite media can be obtained in a film thickness range suitable for high density perpendicular recording.

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  Changes in angular distribution of incident sputtered particles on a substrate were investigated experimentally and by computer simulation. The angular distribution changes significantly with substrate position, sputtering gas pressure, and type of sputtering apparatus. The angular distribution agrees well with the results calculated by computer simulation. The change in angular distribution leads to a change in the film structure. For example, growth of elongated grains was observed in the deposition of iron films by facing target sputtering. This was qualitatively explained by computer simulation to be caused by the oblique incidence of the sputtered particles on the substrate. In addition, computer simulation indicates that an increase in incident particles with high incidence angle results in the formation of porous films with columnar structure so that the control of the distribution of the incidence angle is important to obtain a magnetic thin film with desired microstructure.

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  The sputtering mechanism with the PE target which is a new sputtering source was investigated. Ni-Fe-Nb soft magnetic film was chosen as an example for our study, because it is commonly used as an underlayer of Co-Cr perpendicular recording media. It was confirmed that the target has an advantage to confine plasma in it. Some features of this new target were found to originate from its unique shape. We found that it was indispensable to control the flow of high energy secondary electron in order to suppress the heating up of the substrate, as well as the incident angle control of the sputtered atoms from a target. As a result, low noise media were obtained with this new target.

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  Sputtering process for the voidless boundary growth (columnless microstructure) of Co-Cr thin films was discussed from the point of some experimental results on heat flux characteristics of facing targets sputtering (FTS) method in comparison with planar magnetron sputtering (PMS) method. It is safe to conclude that high heat exchange-energy (heat flux) of adatoms (e.g. more than 1 W/cm² at 1μm/min deposition rate) and less impingement of abnormal energetic particles into the coating layers (plasma free condition) are mainly essential for the suppression process of voided microstructures such as columnar growth of Co-Cr thin films.

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  Co-Cr films deposited at room temperature with an extremely high Ar gas pressure were analyzed with SEM and Auger electron spectroscopy in order to understand magnetic isolation. An SEM observation showed distinctive columnar grain structures in the film that could lead magnetic isolation between the grains. Auger analysis revealed that these films included oxygen not only at the very top surface but also inside the films. The amount of oxygen in the film with a high perpendicular coercivity is much larger than that with a low coercivity especially at the initial stage of growing. The oxidation might occur during and/or after the deposition by penetrating through the air gap-like boundaries of the columnar grains. Such a microstructure of the Co-Cr films seems one of the excellent features for a candidate medium for high density recording.

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  An air introduction effect on Co-Cr film in a new room temperature deposition method was investigated. The coercivity of Co-Cr films deposited at high Ar pressures increased by a small amount of the air introduction to the Ar gas, and a high coercivity of 1500 Oe could be obtained. It was found that some portion of Cr in the films deposited at high Ar pressures were oxidized with little degradation of the crystal orientation, while no oxygen was detected but noticeable amount of nitrogen was observed in the films deposited at low Ar pressures. It was supposed that Cr was oxidized during deposition at high Ar pressures and introduction of the air promoted the oxidation, resulting in the increase in coercivity due to the magnetic isolation of grains. The coercivity would be further increased if kind and amount of the additional gas were optimized.

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  A V-MR head with a track width of 2.5μm was reported. The structure of the head was applied to MR inductive heads with an areal density of 500-600 Mbits/in² and there is reason to believe that the structure can be used to achieve an areal density of over 1 Gbits/in². The structure also has the potential of high TPI and the grounded front gap has the potential of high BPI in near-contact recording.

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  The giant magnetoresistance (GMR) properties in non-coupled type NiFe/Cu/Co/Cu multilayers have been studied for applications such as MR heads. The MR ratios and sharp field dependences of the multilayers prepared on the Cr buffer layer, are enhanced. Influence of the demagnetization and magneto-static coupling effect in patterned GMR NiFe/Cu/Co/Cu films are discussed from experimental and numerical simulated results.

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  The corrosion resistance of an oxide antiferromagnetic NiO film and the exchange coupling between this film and Ni₈₁Fe₁₉ film were investigated for application to MR heads. The corrosion resistance of NiO film was superior to that of FeMn and Ni₈₁Fe₁₉ films. Bilayered 40 nm Ni₈₁Fe₁₉/100 nm NiO films had an exchange coupling field of about 20 Oe and blocking temperature of about 200 °C. An unshielded MR element was fabricated, on both sides of which patterned NiO films were placed. The magnetization pattern of Ni₈₁Fe₁₉ film which exhibited exchange coupling with the patterned NiO films on both sides showed a single domain state. Distortion associated with Barkhausen jumps was not observed in the MR response for the unshielded MR element nor in the reproductive waveform for a shielded MR head either.

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  (111) oriented spin-valve films with Co₉₀Fe₁₀/Cu/Co₉₀Fe₁₀ /Fe₅₀Mn₅₀ structure were prepared on sapphire substrates with c-axis orientation by conventional magnetron sputtering, with CoFe layer thickness as a parameter. The MR (magnetoresistance) ratio slightly increased from 9 to 11 % with decreasing CoFe layer thickness from 100 to 40 Å, while it markedly decreased with further decreasing CoFe layer thickness. Annealed films with 40 Å CoFe layer thickness showed an MR ratio of 13 %. A hard-axis coercivity Hc of 1.5 Oe was obtained in contrast to an easy-axis Hc of more than 10 Oe. It was found that the (111) oriented Co₉₀Fe₁₀/Cu spin-valve films show a high sensitivity of 1% / Oe for rotational magnetization mode.

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  Bit error rates of magnetoresistive heads (MR heads) were evaluated through a partial response maximum likelihood (PRML) read channel. The heads were characterized by utilizing technologies of a shared pole structure, a soft adjacent layer (SAL) for the transverse biasing, and the Fe-Mn boundary controlled stabilizer (BCS) for the Barkhausen noise suppression purpose. The PRML read channel consisted of a sampled data read channel with Viterbi detection, a programmable filter/equalizer for partial response class 4, a three tap transversal filter for adaptive equalization and an 8/9 GCR encoder/decoder.
  Two of the key read/write parameters, the amplitude asymmetry of the readback pulses, which is unique to the magnetoresistive read-out process, and the nonlinear transition shift (NLTS) as the critical measure for the PRML application, were selected for the main objects of the evaluation. Their effect on the bit error rates was investigated. The amplitude asymmetry was found not to deteriorate the bit error rates as long as it was kept approximately within ±15%. However, the error rates rapidly degraded as the asymmetry increased to around 20 % or more. The NLTS due to the less steep gradient of the trailing write field caused by the pole tip saturation, was found to affect and degrade the error rates, significantly. It was also found that the error rate deterioration caused by the NLTS could be effectively suppressed by the write pre-compensation.

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  This paper describes the significance of bilinear and biquadratic inter-layer exchange interactions on the field characteristics of multilayer giant magnetoreslstance (GMR). Sputtered multirayer samples, fabricated in-house are analyzed in terms of these interactions as are some well-known examples from the literature. It is concluded that inter-layer biquadratic coupling is almost always present and can have considerable influence upon the magnetic field characteristics of multilayer GMR systems and spin valves.

We wish to acknowledge partial support from the NSIC/ATP program, U.S. Department of Commerce and (HF) from Hitachi Maxell Ltd. Also thanks to J.A. Barnard for a critical reading of the manuscript.

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  In this paper the appropriate procedures for the magnetic characterisation of granular magnetic materials are reviewed. Particular emphasis is placed on the determination of the energy barrier distribution in the materials which is the most fundamental quantity available, given that the particle size and anisotropy are both distributed quantities. Techniques for the determination of interactions in granular systems are reviewed together with various models of interaction effects with emphasis on a recent Monte-Carlo model which has been particularly successful in predicting resistive phenomena. Finally the dynamic aspects of magnetisation reversal are discussed in terms of the time dependence of magnetisation that results. The implications of time dependence in granular GMR materials are examined. New data showing that resistive effects are themselves time dependent is also presented.

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  Ultra-thin NiFe films for a reproducing single pole head were investigated in terms of controllability of the easy-axis direction. It was found that the uniaxial anisotropy direction did not always coincide with that of the applied magnetic field during deposition in such thin films less than 50 nm thick. The directional control was deteriorated by a lapping micro-surface structure on a glass substrate. Excellent controllability could be obtained when underlayers of Ti, Si₃N₄, and Al₂O₃, excepting SiO₂ was used, although the similar order amplitude of microstructure to the glass substrate remained on the prepared underlayers. It was concluded that compositional differences of the initial growing layer of NiFe films related deeply to the easy-axis directional controllability.

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  The magnetization reversal process in small magnetoresistive head has been investigated. Domain patterns were observed by the Bitter technique. Domain activities and wall state transition in the hard direction were studied in detail.

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  A three-dimensional micromagnetic simulation employing the Landau-Lifshitz-Gilbert equation is performed for an unshielded magnetoresistive (MR) sensor with a soft adjacent layer (SAL). The influence of a non-uniform sense current distribution on the MR response to a cycle of a transverse external field is studied. The field distribution due to the non-uniform sense current distribution is calculated in three dimensions from the Maxwell equation and adopted to the MR sensor simulation. The MR response of the sensor with electrodes on the MR film (type 1) is compared to that with electrodes on the SAL (type2). The maximum output of the type1 sensor is larger than that of the type 2 sensor. The magnetization in the MR film and SAL of the type 2 sensor tilts more from the longitudinal direction than that of the type 1 sensor without the transverse external field (biasing state). This results from the difference in field distributions between the SALs of the two sensors due to the non-uniform sense current distribution.

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  Granular Co-Ag films go through a steep demagnetization process when a permalloy layer is added to them, but slow saturation is maintained in the magnetoresistance (MR) curves. In addition, granular Fe-Ag films prepared under a magnetic field, in which strong magnetic anisotropy is induced, have MR characteristics that are isotropic. This disagreement between MR and magnetic characteristics indicates that ferromagnetic granules are not responsible for the giant MR (GMR) effect. The MR ratio of the granular Fe-Ag film considerably increases when the thickness of the film is less than 20 nm. For such ultra-thin films, the MR curves and the magnetization curves with slow saturation and no hysteresis have features that correspond well with each other. These results show that superpararnagnetism causes the GMR effect in granular systems.

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  The curve of the magnetoresistance ratio versus Cu layer thickness (d_Cu) for Co₈₈ Fe₁₂/Cu multilayers shows the peak at d_Cu =11Å of 20% at room temperature and 36% at 13K. The second peak at d_Cu =24Å, however, is very small compared with Co/Cu multilayers. It is suggested that this small value is concerned with the (111) crystalline orientation.

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  In this paper, we present the experimental results of preparing superlattice magnetoresistance (MR) films and investigate the magnetoresistance properties of MR films which have Cr underlayer or no underlayer. In a lower external magnetic field, the Δρ / ρ₀ of NiFe/Cu multilayer is bigger than that of NiFe/Ti multilayer, furthermore NiFe/Cu multilayers with CoCr underlayer present better MR properties. By properly selecting a group of sputtering parameters, suitable permanent magnet bias layer such as CoCr film can be obtained.

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  Ni-Fe/Cu multilayers with giant magnetoresistive characteristics were prepared by Dual Ion Beam Sputtering apparatus. Multilayers deposited on 50 Å-thick Fe buffer layer exhibited higher MR-Ratio than that without Fe buffer layer. It was found that Fe buffer layers with (100) crystallites orientation played an important role to increase MR field sensitivity ΔMR/ΔH. Multilayers with (100) orientations were much preferable for MR-Ratio rather than that with (111) orientations. [Ni-Fe (10 Å) / Cu (10 Å)]₃₀ multilayers deposited on Fe (100) and (110) buffer layers revealed ΔMR/ΔH at 10 Oe took 3×10^-2 %/Oe and 1×l0^-2 %/Oe, respectively. Simultaneous ion bombardment during film deposition changed the crystallite orientations in multilayers. It was found that MR-ratio and field sensitivity of the film using Fe buffer layer with ion bombardment were improved.

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  Maximum Δρ/ρ change exceeding 4% for a magnetic field increase of 4 Oe is obtained at room temperature in NiFe/Co/Cu/Co sandwiches when two ferromagnetic components, NiFe/Co and Co, with different coercivities are magnetically coupled across a nonmagnetic Cu spacer. It is shown that the MR ratio oscillates as a function of Cu layer thickness and that the magnetic moment decreases under magnetically coupled states. This suggests the presence of antiferromagnetic coupling between the two ferromagnetic components. The measuring field direction which causes high sensitivity for a large MR change rotates perpendicularly to the intrinsic anisotropy axis at about 2.8 nm. This rotating spin-axis direction and very high sensitivity are thought to be due to the phenomenon known as spin flopping associated with antiferromagnetic coupling.

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  The magnetization distribution for GMR heads with non-coupled NiFe/Cu/Co/Cu GMR elements was simulated by magnetic calculation. The output waveform for yoke type heads is more symmetric than that for shield type heads, because, in the yoke type head case, the flux from the medium flows out of the GMR element edge, where the static magnetic coupling between the NiFe and the Co layers exists. The sense current directions in yoke type heads have much influence on the output level, as well as the output waveform asymmetry. The current direction specification raises the output level about 30%. Consequently, it is proved that the yoke type GMR heads have an output level over 950 μ V/ μ m and a symmetric output waveform, according to the parameters optimization.

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  A magnetoresistive thin film head for perpendicular magnetic recording has been designed and developed. The structure of the MR head is a single-pole type and the MR element is placed below the position where the single-pole is cut. It was confirmed by simulation that the MR layer was magnetized enough by the flux from the recorded medium. Reproduced voltages of approximately 1 mV_p-p and SHD less than -30 dB have been obtained with 5 μm track width with more than 24 μm wave length.

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