A special equipment is built up and used to measure two-dimensional dropout distributions on video tapes. The measured distributions are plotted as micrographic picture. The exponential dropout rate distribution is confirmed by the measured data.

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  Co₈₅Cr₁₃Ta₂/Cr bilayered films were deposited by facing-targets sputtering on 2.5-inch Si disk substrates at a substrate temperature of 100°C and an Ar gas pressure of 0.2 mTorr. A carbon protective layer and Z-DOL lubricant were applied on top of the magnetic layers, and their recording characteristics and magnetic properties were investigated. It was found that, although the H_c with a Co-Cr-Ta film thickness of 100 Å was around 800 Oe, the linear-density response and noise properties obtained when a magnetoresistive head was used were comparable with those of a disk used in current products with an H_c of 2.4 kOe, which was employed as a reference. TEM images were observed to investigate what magnetic grains exist in the film and why the recording characteristics were comparable. The grains have unclear boundaries, which look like amorphous structures. For these reasons, the disks are expected to be used for high-density recording.

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  In this paper, we discuss the track-edge noise characteristics in perpendicular media in comparison to longitudinal media. The composition of the magnetic layer was the same in each medium. We found that the track-edge recording characteristics of perpendicular media were very different from those of longitudinal media. Cross-track profiles of normalized medium noise in perpendicular media, considered as a whole, is higher than in longitudinal media. In longitudinal media, distinct track-edge noise was observed, but in perpendicular media, the track-edge noise level is lower than on-track noise. The reason for the low track-edge noise characteristics in perpendicular media is due to a suppressed demagnetize field around the track edge, which results in a sharp track-edge shape. Furthermore, the side-erasure width in perpendicular media is narrower than that in longitudinal media, and is less dependent of the yaw-angle.

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  A recording scheme employing combined perpendicular and longitudinal modes is proposed here. An isolated transition is composed of a regular longitudinal transition and a pulse magnetization in the perpendicular direction. The perpendicular component directs the short wavelength flux favorably toward the head. The isolated pulse in this recording mode has a similar waveform to that of a longitudinal medium but with greatly reduced PW50. Furthermore, the combined perpendicular and longitudinal recording offers improved thermal stability as well as channel compatibility with existing recording systems. Methods to achieve this recording mode by controlling the medium's orientation ratio are also discussed.

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  The key technique to apply keepered media system is how to ‘open‘ the keepered layer. In this paper, we would propose a new concept of keepered-media-reproduction with Dual MR heads. The keeper layer could be biased by the stray flux from DMR sensors. The shunting-releasing ratio between reproductive signals without and with sense current is found to be -26.6 dB. This is a completely-stable medium system against thermal demagnetization. It is believed that keepered media may offer a similar advantage with MR heads and potentially allow magnetics to break the 10 Gb/in² areal density barrier due to the high performance gains of MR heads.

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  Thermal fluctuations in magnetization of longitudinal and perpendicular magnetic recording media was calculated using the Monte Carlo simulation method. From the simulation results and by considering that thick media (>30 nm) can be used in perpendicular recording, we concluded that perpendicular recording is superior to longitudinal recording in terms of thermal fluctuations. Signal dccay duc to thcrmal fluctuations incrcascs with increasing grain size distribution when decay is small, but decreases with increasing grain size distribution when decay is large. The signal decay is larger at higher density in longitudinal recording, and it is smaller at higher density in perpendicular recording.

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  A computational model of thermally activated magnetisation reversal in particulate materials is described. The model allows the study of the detailed relaxation behaviour of isolated (non-interacting) particles. Computed results show non-exponential relaxation over small energy barriers attributable to the absence of a unique relaxation time. The coercivity shows a rapid increase at very short measurement time which is important as regards ultimate switching speeds in recording. The effects of interparticle dipolar magnetic interactions are also introduced into the model. These have the effect of increasing the spread of relaxation times via the inevitable dispersion in the magnitude and direction of the local field.

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  The thermal stability of written bits in 8 Gbit/in² CoCrPtTaNb media is investigated using magnetic force miscroscopy (MFM). The MFM tip sensitivity is “calibrated” using recording patterns that are stable over the time scale new patterns are being examined. This allowed the determination of the dependence of the MFM signal as well as the signal-to-noise ratio with time as in a spin stand. Analyses made on written tracks on media at room temperature with different magnetic layer thickness δ showed some signal decay for δ ≤ 16 nm but stable behavior is observed for δ = 25 nm. Bits subjected to a 31-hour anneal at 473 K also exhibited no significant degradation suggesting the accessibility of thermally stable > 10 Gbit/in² recording in the longitudinal mode.

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  The magnetization decay in CoCr-alloy perpendicular magnetic recording media has been investigated. Both remanent magnetization and recorded signal output decay rates of CoCrPtTa medium increase with decreasing magnetic layer thickness. The decay rates can be kept small by controlling the microstructure of magnetic layer by employing a CoCr₃₅/TiCr₁₀ dual-underlayer. CoCrPt media with the dual-underlayer have high Mr/Ms ratio (Mr/Ms > 0.95) and show little decay of remanent magnetization and recorded signal output, though the magnetic layer is very thin (25 nm) and is composed of small grains. It is possible to prepare perpendicular media comprising a Co-based alloy with Mr/Ms > 0.95, which is an important factor to suppress the recorded signal decay rate within an acceptable level.

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  The temperature dependence of the magnetic viscosity coefficient (Sv), the activation volume (Vact) and the coercivity (Hc) were examined for CoCrTa/Cr and CoCrPtTa/Cr thin films in the temperature range from 200 to 423 K. This experiment shows that the medium noise measured for 150 kFCI is approximately proportional to kT/Sv (=Vact × Ms) at 298K. kT/Sv and the temperature variation of coercivity (dHc/dT) increase with increasing temperature. The relationship, H_A/50Sv > 1 was obtained from the thermal stability of magnetization, where H_A is the anisotropy field. However, in practice one must compare Hc instead of H_A with 50Sv. The factor Hc/50Sv, a measure of the thermal stability of the magnetization, was close to 1.3 -1.7 at 373 K.

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  From measurements of the time dependence of the magnetization, the thermal activation volume in various materials for recording media was deduced and its relationship with the magnetization reversal mode studied. With this aim, the materials were analysed in different conditions which can affect the basic processes of magnetization. The activation volume results depending on the magnetization switching mode. In particles with good morphological and structural order the activation volume approaches the physical volume of the particles. On the contrary, when different conditions pertain, e.g. imperfect morphology, addition of doping ions, effects of interparticle interactions and temperature, make more probable the occurrence of an incoherent, or heterogeneous, switching, the activation volume is relatively smaller. It indicates a direct relation of the activation volume with the region of material acting as center of nucleation of the reversal.

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  This paper investigates magnetization time decay for thin film recording media, Co-Ni or Co-O ME tapes and Co-Ni-Cr-Ta, and Co-Cr sputtered hard disks. Emphasis was placed on temperature effect on magnetization time decay, fluctuation fields, and activation volumes. It was clarified that fluctuation fields changes as the environmental temperature changes, but the change was different according to the composition of thin films.

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  Coercivity and magnetic aftereffect of nanocrystalline L1₀ type FePt films is discussed in connection with magnetocrystalline anisotropy and grain size. Magnetocrystalline anisotropy field shows very large value up to more than 40kOe dependent on annealing temperature. This large magnetocrystalline anisotropy enabled to maintain large K_uV/kT value more than 40 (10 years stability) even with very fine grain size of 7∼8 nm, which described the potential of this alloy film to resist thermal fluctuation of magnetisation. Although intergranular exchange coupling enhances the thermal stability of the films, it is successfully described that the change in magnetic viscosity is qualitatively coincident with that of K_uV/kT value. Activation volume V_ac of these films is much larger than grain volume, which is likely to be attributable to the existence of intergranular exchange coupling.

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  Thermal relaxation is becoming more and more significant as bit sizes are decreased to achieve high recording density. In this paper a separate read and write system, replacing the low read sensitivity single-pole head with a MR reproducing head and a regular SPT writing head, was used for experiments to measure the reproduced output reduction in double-layered media. The influence of the single-pole writing head during the reproducing process is brought out. Then, some simulation results associated with a curling switching model are also discussed.

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  The decay times of information recorded on perpendicular and longitudinal recording media were measured with a commercial MR head. We confirmed that the recording information of both types of media decayed with time. Longitudinal recording media showed a large time decay at higher linear densities, caused by an increased demagnetizing field. On the other hand, perpendicular media showed a large time decay at low densities. We produced a triple-layered perpendicular medium (CoCr19PtTaNb /paramagnetic buffer layer/soft magnetic underlayer) to inhibit thermal fluctuations at low densities so as not to decrease the SNR.

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  The Boeing Company's changing business process and application environments are placing pressure on the systems people to provide integrated systems solutions that will fulfill storage, processing, data management and performance requirements. The delivery systems requirements to support Boeing applications provide a backdrop for the systems issues that are being addressed in this paper. A storage solution -on-line, near-line, and off-line - has become a major concern. A solution to the management of data and mass storage is becoming one of the "grand challenges" facing the computer industry and systems integrators and architects today. This paper addresses the mass storage information management and related issues.

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  Many multimedia applications demand real-time and high throughput data retrieval from a storage subsystem. Very often, the access pattern of such retrieval has random nature. This is due to real-time playback of video clips that are physically separated on the disk platter (non-linear editing), or due to serving many independent clients simultaneously (VOD; video on demand).
  In this paper, we describe a new real-time disk management algorithm that can significantly reduce the overhead incurred by random access. While existing algorithms treat the rotational delay as uncontrollable, our algorithm controls both seek and rotational delay by proper scheduling and data placement so as to reduce overhead in a random data access environment.

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  We developed a higher performance and lower cost Disk Array ( RAID ) system. It is based on software RAID and uses hardware accelerator for parity generation and others. The RAID control software is implemented as a device driver of an operating system and it executes address translation, cache management and hardware control functions. To reduce write penalty of RAID-5, we proposed new data update method named Delayed Parity Generation and new data-parity placement method. A Prototype shows twice performance in typical Database environment comparing with conventional RAID-5.

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  We have studied storage subsystems for multimedia servers in application systems that require huge storage capacities. The importance of multimedia servers has grown recently due to the increasing popularity of online services such as home shopping and video-on-demand. In this paper, we describe an architecture suitable for high-speed transmission of multimedia data. We also explain the characteristics of our Multimedia Stream Adapter (MSA), which we developed based on this architecture. Using this technology, we have built the Fujitsu Media Server^*1, which is capable of providing the most cost-efficient multimedia information system available.

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  In conventional method, discontinuous sectors in disk processing must be transferred by individual operations even they are in the same track. When cache stage/destage operation starts, rotational latency can not be avoided. We pursue a novel cache schedule strategy COCS ( Continuous Operating Cache Schedule) which enables transferring data of discontinuous sectors in a single operation, minimizes the rotational latency. It can ever get zero-latency in some case. Experiment results illustrate that COCS has better performance.

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  A disk array structure based on PCI-SCSI adapter and some SCSI disk drives is given and a multi-threaded I/O algorithm is presented in the paper. The time sequence of the multi-threaded I/O scheduling is analyzed. Compared with the sequential I/O, the response time for the multi-threaded I/O is reduced greatly, especially for that the disk service time is large and/or the I/O data size is large. The multi-threaded I/O is one of ways to get high performance in disk array.

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  Redundant Array of Independent Disks (RAID) is the most efficient way to avoid the bottleneck problem between I/O subsystem's performance and the CPU processing power. This paper describes a novel RAID architecture, called FlexArch, which can meet ditferent requirements in different application environments. It is very convenient for the different users to define and construct a kind of RAID architecture according to its application environment. Two kinds of special structures, RAID_table and RAID_map are proposed in order to implement FlexArch. Based on these two structures, the scheduling algorithms for the read/write operations on FlexArch RAID are also given.

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  We have successfully demonstrated that the new biasing spin-valve GMR head i.e. hard magnets underlaid/leads overlaid structure, has excellent readback characteristics in submicron trackwidth. The head resistance with 0.7um trackwidth and 0.7um height was 30 Ohm which was extremely low . A microtrack profile showed the head had 0.7um effective trackwidth with a good left-right symmetry. The microtrack profile was not affected by misregistration between leads and hard magnets. The head structure potential is superior not only in reading charecteristics but in productivity.

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  The giant magnetoresistance of magnetic supedattice which consists of cobalt and simple metal is calculated using the first principle calculation based on local spin density approximation. It can be estimated that Co/Mg superlattice has large exchange splitting and the large ‘giant magnetoresistance’ effect can be obtained if the anti-parallel configuration can be realized. The electronic structure of Co/Mg superlattice is similar to that of Co/Cu supedattice. The up spin d-band of Co/Mg superlattice is fully filled in parallel configuration and the d-hole exists in anti-parallel configuration. For Co/Al superlattice, we also find that the MR ratio is large.

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  The Co-Au granular films have been prepared on glass substrates by rf sputtering. The magnetization curve exhibits the superparamagnetic and ferromagnetic natures. When the Co composition, x, decreases, the superparamagnetic nature increases, and the giant magnetoresistance (MR), which comes mainly from the superparamgnetic granules, increases up to about 2.5 % at x ≈ 23 at%. When the film is annealed, the granules grow keeping the superparamgnetic nature, and so the change in the resistivity, Δρ, is held almost constant up to 250°C. The MR ratio increases on annealing and shows the maximum value of about 2.5% at 300°C. Annealing above 300°C causes the magnetism change from the superparamagnetic to the ferromagnetic due to the grain growth above the critical size, resulting in the decrease of Δρ: Furthermore, the growth of the ferromagnetic (111) oriented Co grains causes the increase in the perpendicular anisotropy.

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  By inserting only 0.75 nm-thick Cu underlayer between the IrMn/CoFe/Cu/CoFe spin-valve stack and Ta underlayer, the MR ratio was about 1.8 times as large as that without the Cu layer. XRD and magnetic measurements suggest that the Cu "islands" formed in the initial growth stage modify the interfaces of the spin-Valve, resulting in the enhancement of the spin-dependent scattering. When the Cu thickness (t) was larger than 1.5 nm, the MR ratio and coercivity of the free layer were increased and decreased, respectively, in comparison with those of t=0 nm. This was due to the considerable increase in the crystallinity of the spin-valve films. Namely, Cu is expected to function as the buffer "layer" in this thickness range. The inductive/spin-valve composite heads using a material developed in this study were stable and quiet in the dynamic performance.

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  The three-dimensional micromagnetic simulations of submicron spin valve (SV) heads are presented. At such sensor widths, the amplitude of SV head output is reduced. An effective way to improve this reduction is to weaken the longitudinal bias field from permanent magnets. Results of simulations reveal that the magnetizations of the pinned layer near the air bearing surface rotate irregularly below a critical permanent magnet strength at a positive external medium field. This irregular rotation causes hysteresis of transfer curve. The critical permanent magnet strength decreases linearly with an increase in the reciprocal of the square of the sensor width. At the optimum permanent magnet strength, the amplitude of the sensor with 0.3 μm wide is almost the same as that of the sensor with 1.0 μm wide. It is important to evaluate the domain stability of the pinned layer when designing a SV head with submicron sensor widths.

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  Co₉₀Fe₁₀/Cu/Co₉₀Fe₁₀/Ir₂₅Mn₇₅ spin-valves with Ta buffer layer were prepared by ion beam sputtering. Improvements in physical properties were obtained by adding H₂ to Xe sputtering gas. Specifically, coercivity in the CoFe free layer considerably decreased with increasing H₂-flow rate. In addition, exchange coupling between the IrMn and pinned CoFe layers became stronger in the preparation under the higher H₂-flow rate. X-ray diffraction, transmission electron microscope, and secondary ion mass spectroscopy observations suggest that micro-crystallization of each layer is responsible for improving the physical properties.

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  Ni₈₁Fe₁₉/Fe₅₀Mn₅₀ bilayers were deposited by using dual ion beam sputtering apparatus which can control the crystallographic structures at interfacial monoatomic layers of the multilayers by ion bombardment to the growing film surfaces. In this study, Ar ions were bombarded to the interfaces of Ni-Fe/FeMn bilayers. The relationship between the structure at the interfaces and the exchange coupling field H_ex. were investigated. Ion bombardment to the interfaces at proper energy promoted (111) orientation of FeMn crystallites to increase H_ex. between Ni-Fe and FeMn layers. Ion bombardment to 2∼20 monolayers at the interfaces promoted crystallization of FeMn layers while the ion bombardment to the whole FeMn layers suppressed any crystallization.

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  Spin valves containing NiFe and Co magnetic layers were prepared with the objective of determining suitable film parameters for incorporation into a read head. A micromagnetic computer model was used for theoretical calculations of the MR and good agreement with experimental results was found.

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  Based on the micromagnetical model, the distribution of signal field and magnetization in the free layer are analyzed, the correlation between the head performance characteristic and head geometric parameters have been simulated by putting the head on a suitable front-end electronic circuit. The result shows that output voltage signal has good linear characteristic with respect to the medium recording signal in a wide range of gap length. The optimal values of sensing current should be selected between 10mA and 60mA, the linear geometric parameters for gap width are at the range of g₁+g₂ ≼ 0.7um. According to these simulated results, we also fabricated NiFe/Cu/Co/Cu spin-valve head on the glass substrate by using a magnetron aputtering system. Its variations of giant magnetoresistance are between 3% and 8% (40∼100Oe) at room temperature.

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  A yoke-type GMR head with a vertical configuration where the sense current flows through the magnetic yoke films was studied. A large magnetoresistance change was obtained for test structures on a wafer consisting of a spin valve GMR sensor and CoZrNb yoke films. It was also found that offsets in the response curves were observed depending on the overlapped area between sensors and yokes.

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  The partial response class 5 (PR5) signal processing for perpendicular magnetic recording with single layer media is discussed. Several benefits of the PR5 system to channel coding and Viterbi detection are shown: applicable to both the d=0 code and the d=1code, interleaving signal processing, and the four-state in the Viterbi decoder. Basic configurations of the timing recovery for the PR5 system is also shown.

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  Partial response maximum-likelihood(PRML) systems using an MR head and a double layer perpendicular medium are studied. The bit-error rate performance of PRML systems characterized by the polynomials with the positive coefficients for the (1,7) code and the negative coefficients for the 8/9 code is evaluated. The PRML system for the (1,7) code has a large minimum Euclidean distance and a small noise spectrum compared with those for the 8/9 code. This results in a significant performance improvement. Among PRML systems discussed in this study, PR(1, 2, 3, 2, 1)ML exhibits the best performance and improves the SNR by about 13.8 dB over that of PR4ML for the 8/9 code at a bit-error rate of 10⁻⁴ and a normalized linear density of 2.5. PR(1, 2, 2, 1)ML, PR(1, 3, 3, 1)ML and PR(1, 2, 1)ML also show excellent performance.

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  An application of the neural network equalization to the partial response maximum-likelihood(PRML) channel with nonlinear distortion in magnetoresistive(MR) head and partial erasure is studied. First, a model of the recording/reproducing channel with the nonlinear distortion in MR head and partial erasure and the neural network equalizer are described. Then, the bit error rate(BER) performance for PRML channel is obtained by computer simulation and is compared with that of the conventional transversal equalizer. The results show that the BER performance of the neural network equalizer is better than that of the conventional transversal equalizer.

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  The trellis code and its application on PR channels, named a TCPR system, is well known as one of the recent breakthroughs on record coding. On the other hand, it is feared that the TCPR system might incur disadvantages on bit error rate (BER) performance at higher recording densities due to the fateful deterioration of the code rate. In this paper we study the applicability of the TCPR system with a PR I channel at a higher linear density that is more than three times the bit cell interval of the input date sequence, and compare it's BER performance with that of the uncoded baseline PRML system. Results show that the dependancy of the code rate on the TCPR system with a PR I channel is more remarkable than the uncoded baseline PRML system.

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  A new multitrack coding scheme is proposed as a preferable use in perpendicular recording using a double layer medium and an MR head. The coding uses combinations of three codes in 8 orthogonal codes based on Hadamard matrix elements. The new coding method has a high code rate and reliability because of the multilevel correlation detection due to simultaneous reading of three tracks. The performances are investigated by theoretical calculations, simulations and experiments.

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  To achieve the highest capacities, inevitable tradeoff leads to channels with relatively low signal to noise ratio (SNR). So the magnetic research channel is stepping into the fields of weak signal processing in the background of strong noise. In this paper we describe a decision feedback equalization scheme of potential well trigger for low SNR magnetic recording signal extracting, the result of performance evaluation is also presented.

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  This paper describes the ex- perimental results of high resistivity granular films with soft magnetic properties. After estimation of the resistivity needed to suppress eddy current loss at over tens of MHz, we investigate material parameters governing formation process and thermal stability of the granular structure that realizes this resistivity. Furthermore, we propose a model of the extraordinarily high uniaxial anisotropy which has been frequently observed for the granular films and present some experimental evidences.

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  Soft magnetic films for head core materials with high saturation magnetic flux density prepared by electroplating and electroless-plating were discussed. Especially, magnetic properties for electroplated NiFe based films, electroplated FeP based films and also electroplated CoNiFe based films and finally electroless-plated CoFe based films were summarized.

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  Higher saturation magnetic flux density Fe-Al-Si films have been prepared by the method of evaporation in argon atmosphere. Control of both argon pressure and substrate temperature makes it possible to obtain the Fe-Al-Si films with both high saturation magnetic flux density and soft magnetic properties. The saturation magnetic flux density of the films was 1.5T, and the initial magnetic permeability was higher than 4000. The maximum of initial magnetic permeability has been obtained at an argon pressure of 2x10^-4Torr and at a substrate temperature of 673K. The deposited films were annealed at 923K in vacuum ambience.
  The magnetic head utilizing the higher saturation magnetic flux density Fe-Al-Si films showed good recording characteristics.

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  A high frequency permeability for an electroplated CoNiFeS film having high saturation magnetic flux density(B_s) of 1.7T and high resistivity(ρ) of 51μΩ-cm was investigated in comparing with CoNiFe film having ρ=25μΩ-cm value. Both films had suitable thermal stability on magnetic properties up to 300°C and magnetic anisotropy(H_k) could be controlled by annealing with magnetic field. Higher permeability of the CoNiFeS film could be attributed to decrease the eddy current loss based on twice higher resistivity compared with the CoNiFe film.

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  A GMR/inductive dual head with submicron track widths is proposed. The track width is defined by the thickness of a film magnetic core. The head has read and write cores with an outer diameter of 12 μm and 22 μm, respectively, and have high efficiency due to a new design with an extremely short flux path. It was found by computer simulation that the optimized write core could write on a medium with an H_c of 2 kOe even with a 1 turn drive coil. The structural design, advantages, and performance of the new head are discussed.

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  A thin film magnetic head for perpendicular recording was developed by the combination of a single pole transducer and a low flying slider. FeZrN sputtered film with high saturation magnetization was employed as a main pole of the transducer and the slider was designed from fluid dynamics calculation to achieve very low flying height. The read/write characteristic of the head at 25 nm flying height using CoCr/NiFeNb media were 350 n Vp-p/ μm·m/s· turn at 15 kFCI and -34dB in overwrite. Performance of the head when combined with high Bs material for the main pole, high Hc and thin recording layer for the medium, and low flying height of the slider was discussed from the point of high density recording.

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  The write head design for a merged MR head needs to be optimized to obtain a good write performance for a perpendicular magnetic recording application. We fabricated a write-only single pole head with the simplified structure which consists of a main pole and a thin film coil without a return yoke. The write performance of the single pole head with double-layered media was evaluated by using an MR read head. The O/W value obtained was less than -35dB, and the PW₅₀ value obtained from the differentiated curve of the readback waveform was 0.20μm. The small PW₅₀ from the recorded bits attributes to the sharp magnetic transitions.

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  Investigation of magnetic fields created by the multilayer MIG heads is carried out with the help of magnetooptical method of measuring of magnetic fields in microvolumes. The fields created by the secondary gaps of heads were observed. The results of direct measuring of fields are in agreement with the measured playback frequency responses of heads.

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  This paper compares the head field components and replay characteristics of a single pole head with a variable potential distribution with those of thinner conventional constant potential single poles. Grading the magnetisation is shown to increase significantly the usable frequency range, and to reduce the output pulse width.

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  A new head design of a planar configuration for multi track perpendicular magnetic recording is proposed. The new planar multi-track head consists 4 single-pole-type inductive write heads and 2 ring-yoke-type spin-valve MR read heads. In reproducing process, each MR head can read simultaneously signals from two tracks all together. To realize close-packed track recording, length direction of magnetic yoke of the write heads and head pole are arranged in the track and scan direction, respectively. Though this head consists of even 6 head-elements, the head fabrication process is almost the same as that of a conventional planar head.

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  The relationship between the off-track and the amplitude asymmetry of MR signal is investigated. It is found that the amplitude symmetrical point of MR signal is neither at the geometric track center nor at the magnetic center (the peak position of track profile). The amplitude asymmetry is a monotonic function of off-track position. This phenomenon is related to the anisotropic flux propagation in the SAL. The effect of off-track on the shape of readback pulse of MR head is also studied. An extended Lorentzian model is used to characterize the flux passing though an MR head from an isolated transition. The results indicate that the order N of this model is different for different MR heads.

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