A basic model was developed for 3-dimensional analyses of the magnetic recording and reproducing processes. The curling magnetization reversal model used in our conventional 2-dimensional simulator was improved to calculate the 3-dimensional direction of a megnetization vector in a recoding medium. To consider the nonlinearity of a soft magnetic material, a recording head and an unser-layer of a Co-Cr/Ni-Fe double-layered medium were modeled by arctan function M-H loops. The magnetic field distribution was calculated by the magnetic charge distribution in both head and medium. The 3-dimensional distribution of the SPT head field was investigated when the head was combined with a Co-Cr/Ni-Fe double-layered medium.

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  The mean interaction field were calculated by a 3-D numerical model for a longitudinally oriented Ba-ferrite and a metal particulate recording media. The model was composed of regularly arranged rectangular parallelepiped particles. The influence of the orientation distribution was also investigated. The negative interaciton field is brought by particles whole easy-axes are parallel each to each, while series particles give the positive field. Therefore the positive mean field was obtained for the Ba-ferrite medium because the distance between series particles was much shorter than that between parallel particeles. When the orientation distribution became broad, the mean field decreased because the interparticle distance between series particles increased and it between parallel particles decreased. On the other hand, the negative mean field was obtained for the metal particulate medium.

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  Interparticle interaction was discussed by measuring Henkel plots and delta M plaots for various magnetic media, such as Co-γ-iron oxide tape, metal particulate tape and Ba ferrite particulate tape. It was ascertaind that only negative interaction acts for the parallel and the transverse directions to the orientation direction, for both non-oriented and longitudinally oriented acicular particulate tapes, and that positive interaction acts for the orientation direction for platelet-shaped Ba ferrite tapes, negative interaction for their transverse direction, and almost zero interactin for non-oriented Ba ferrite tapes. Interaction field strength was estimated for these media, by means of linearization of Henkel plots, based on mean-field concept.

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  Read-write characteristics of the obliquely evaporated Co-CoO film were investigated. Symmetric wave-form was observed in magnetic motive force (M.M.F.) of 0.13 ATop. But it changed asymmertrically with broad tail when M.M.F. increased above 0.13 ATop. On the other hand, media noise of dc-erase, ac-erase and modulation had the maximum values in M.M.F. of 0.13 ATop. These noise properties were thought to be related with rewriting in the surface of the film by head trailing side field.

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  This paper provides the analysis of the write and read spacing loss phenomena for perpendicular recording. Double arctangent transition model including magnetization decay away from a transition revealed the wavelength dependence of the write spacing loss factor. The wavelength dependence of the read spacing loss factor has been found to be influenced by the strength of the head-to-medium magnetic interaction, showing the difference between single pole type and ring heads.

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  Fine acicular barium ferrite particles(long axis: 0.24μm, aspect ratio: 4.5) were prepared by the sintering method. The acicular barium ferrite magnetic tape was fabricated with these fine acicular particles. The output waveform of this tape signified that it had the perpendicular magnetic anisotropy. The surface of this tape was more smooth than that of previously prepared tape. Therefore, the reduction of spacing loss resulted in the high value of signal output in the high frequency.

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  CoCrTa thin films media with Cr underlayer have been widely used for the medium of rigid disks. Since most of the noise associated with medium is the transition noise due to zigzag domains, the noise increases linearly with recording density, and is a serious problem to obtain the high-S/N medium at high transition densities.
  We found that the noise of CoCrTa/Cr medium with high Cr-Ta Concentration is half that of conventional CoCrTa/Cr longitudinal magnetic recording medium, and independent of the transition density.
  We considered the material's micromagnetic mechanism using experimental results for the angular dependens of Hc, δM, and rotational hystersis losses. These consideraton have led to folloeing model. At higher concentrations of the nonmagnetic elements, Cr and Ta, the easy axes of magnetization are parallel to the surface in initial layer of CoCrTa, on the other hand, in near the surface of CoCrTa layer, the easy axes of magnetization rises from the film surface, and the intergranular ferromagnetic exchange couplings is less. The perpendicular magnetic anisotropy and/or suppression of intergranular coupling, reduces the noise of CoCrTa/Cr medium.

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  The Co-Cr disk media for perpendicular recording were prepared by sputter-deposition at high Ar pressures which enables low voltage discharges. The magnetic structure and the noise characteristic of the disk media were investigated. It was found that the Co-Cr medium deposited at a high Ar pressure showes a high perpendicular anisotropy field of about 5 kOe as well as a high perpendicular coercivity even if the medium is deposited at room temperature. The high anisotropy field is supposed to be originated from the crystalline anisotropy by the temperature dependence of the coercivity. The angular dependence of the coercivity and the low noise characteristic, which are almost the same as those of a medium prepared at a low Ar pressure and a high substrate temperature, suggest that the magnetization reverses mainly by a rotation mechanism and the magnetic particles are well separated. It was concluded that the media prepared at high Ar pressures have a fine and isolated magnetic structure, which might be one of the suitable structure for high density recording.

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  The magnetic properties and recording characteristics of CoCrTaPt/NiFe double-layered perpendicular media have been investigated. Thin CoCrTaPt layered media have high coercivity and good recording performances. CoCrTaPt/CoCrTa/NiFe triple-layered media have higher coercivity than CoCrTa and CoCrTaPt/NiFe media. But the output and media noise of triple-layered media are lower than these of CoCrTaPt/NiFe media. The microstructure invistigations of these media suggest that recording performance might be explained on the basis of intergranular exchange coupling theory.

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  A novel pre-embossed rigid magnetic (PERM) disk using a 65mm-diameter molded plastic disk substrate has been developed. Runout characteristics of the plastic disk were investigated using a fast Fourier transform method and we found that the plastic disk had a low runout value of 3.0μm at a frequency of 120 Hz that was to be sufficient for a practical use. Magnetic and electromagnetic characteristics of a laminated CoCrPt/Cr magnetic film sputtered on the substrate surface were also evaluted experimentally and theoretically, and the recording capability of a bit density in excess of 400 Mbit/(inch)² in the PERM disk was shown.

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  Frequency dependence of the efficiency for thin film megnetic heads is studied by analysis of equivalent circuit method and large scale model. The core characteristics reflect directly on the head performance because of a small amount of magnetic core material. The eddy current loss at the back-contact region has no effect on the head efficiency below several tens of megaheltz. In order to develop the thin film head for high frequency use, frequency dependence of the magnetic core permeability must be improved, such as by laminating films.

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  A laminated FeTaN films head of high saturation flux density was developed and read-write characteristics in high frequency range was measured. Recording characteristics in short wave length excels in the head with narrow gap length and this characteristic is maintained to high frequency greater than 80 MHz. The laminated FeTaN film head needs less current than a laminated amorphous film head for optimum recording.
  One magnetic layer insulated by quartz of the laminated FeTaN film head was devided into three sub-layer and magnetic anisotropy of each sub-layer was controlled. This double-structured FeTaN head reproduced same level single as amorphous head.

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  Quantitative permeability measurements of soft magnetic films were carried out using the inductance variation and the calibiration obtained by 3D-FEM calculations. In order to obtain the absolute value of the permeability, the distribution of the magnetic field from the coil and the magnetic film were calculated. The calibration value depends on the coil shape, film thickness, and the permeability itself. We obtained the calibration factor for the films in the range between 0.5-10μm in thickness and 1-20000 in relative permeability.

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  Some interesting results for longitudinal magnetoresistance effect, such as trackwidth independence of output amplitude, have been achived theoretically and experimentally. It is believed that longitudinal magnetoresistance effect is more suited for narrow trackwidth perpendiculer magnetic recording.

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  We studied magnetic properties of substrate/30nmNiFe/50nmCo_xMn_1-x systems. As a result, the shift of the hysteresis loop (He₁) was measured at the condetion of x = 0.19∼0.39 in as-made state. the maximum value of He₁ was about 20 Oe. At the point of corrosion, CoMn films were superior to FeMn films.

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  The magnetization configurations of soft adjacent layer(SAL) biased MR heads with the longitudinal bias were analyzed using the micromagnetic calculation. The magnetization rotation in MR film is promoted by the contrary rotation in SAL. The magnetization rotation due to SAL is larger in the MR film stabilized by untiferromagnetic films than that stabilized by permanent magnet films.

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  Co₉₀Fe₁₀/Cu spin-valve structures were prepared by RF and DC magnetoron sputtering method. X-ray diffraction data showed that the spin-valves pn sapphire substrate exhibited good fcc (111) preferred orientations. The maximum value of Δρ/ρ₀ was 11% which was larger than that obtained for Co/Cu spin-valve structures.

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  Dual truck complementary head has been proposed in this study. It was confirmed that the recording mechanism was correct in principle through the read-write charactristics using conventional thin film head. Thin film with giant magneto-resistivity GMR ratio is required to construct the hybrid type of read-write head. Ni-Fe/Cu multilayers with Cu layer thickness of 10Å prepared by ion beam sputtering method exhibited high magneto-resistivity (MR) ratio as large as aobut 16%. The multilayer seemed to be suitable for detecting of flux reversal in dual truck complementary heads.

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  The recording of characteristics perpendicular-longitudinal composite double-layered media (CoNiReP perpendicular layer with CoP longitudinal recording underlayer) were examined by using ring-type head. Addition of longitudinal recording underlayer enhanced the reproduced output especially in lower density region. It was considered that such an enhancement was caused not only by superposition of output from perpendicular layer and underlayer, but also by relaxization of demagnetization. Moreover, the reproduced waveform was obtained as a single-peaked pulse regardless of the magneto-motive force, suggesting that the residual magnetization state of the composite medium is the "phase synchronization mode." On the other hand, the reproduced waveform of the composite medium whose underlayer coercivity, Hc(u), was 1200 Oe was observed as di-pulse, indicating the change in the remanent magnetization state due to the variation in the underlayer coercivity. These results suggest that it was able to control the remanent magnetization state of the composite medium by changing the Hc(u), and the possibility of realization of excellent characteristics by optimization of medium parameters of composite media was confirmed.

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  The recording noise of sputtered Co alloy media at high recording density was studied with readback waveform. High noise power of longitudinal recording media at high recording density was correlated to the fluctuation of magnetic transition region. In perpendicular recording media, in contrast, the fluctuation of magnetic transition region was small even at high recording density, which leads to low noise power.

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  Investigated is noise characteristics of vacuum-deposited Co-Cr tapes with regard to the incident angle of vapor beam onto substrates. For the Co-Cr film, medium C, deposited with the incident angle varying from 70° to 20°, modulation noise level is high and increases as the carrier frequency increases. While for medium A deposited with the incident angle varying from 20° to −20° and medium B with the angle from 55° to 20°, modulation noise level is relatively low and remains almost constant with increasing carrier frequency. Bitter patterns suggest that modulation noise of medium C originates from large longitudinal magnetization component resulting in zig-zag transitions. Modulation noise level of media B and C depends on head scanning direction, being the smaller in the normal scanning than in the reverse scanning. Recording process of medium A corresponds to that in the reverse scanning of media B and C. It follows that modulation noise level of medium B in the normal scanning is lower than that of perpendicularly deposited medium A.

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  The recording characteristics of a perpendicular medium are strongly affected by surface roughness. A smoother surface means closer head-to-medium spacing and so better recording characteristics, especially with a contact head. We report recording characteristics and media noise with a double-layer perpendicular disk having a smooth surface and contact head.

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  The magnetic and recording characteristics of Co-Cr-Ta tape were investigated. The Co-Cr-Ta tape was prepared by facing targets sputtering (FTS) system.
  The magnetic characteristics of Co-Cr-Ta tape such as crystallinity, H_k and ΔH_c/H_c were improved by adding a small amount of Ta to Co-Cr film as a third element and using Kr as a sputtering gas.
  Recording characteristics at short wavelength of the Co-Cr-Ta tape were investigated using a helical-scan VTR machine. Reproduced output of 85 nV_o-p/(μm·T·m/s) and a C/N of 54.5 dB(R.B.W.=30kHz) were obtained at 150kFRPI.

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  Overwrite recording is very popular, but there are few studies of re-recording phenomena. In this paper, the re-recording dip is explained by the newly introduced "contact printing model." The previously recorded signal can be transferred onto the overwritten signal area by the bias effect of the over-written signal's magnetic flux. This model can be confirmed by some experiments including the phase measurement at both area after and before re-recording dip.

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  Saturation recording is commonly used in hard disk drives. i.e. new data simply record over old data as referred to overwrite (O/W). Thus, old data are erased without any special erasure process. However, when O/W ability is not sufficient, distorted isolated pulses are induced in perpendicular magnetic recording, because residual overwritten noise acts as a noise. We have focused on studying DC erasing of recorded signal to clarify the mechanism of erasing phenomena in O/W. Demagnetizing Field in recorded bit has effects on magnetic field generated by pole. Therefore the magnetic field is not able to saturate magnetic layers of disk, and previously recorded signals remain and distort new signals to be recorded over.

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  The shift of transition position depending on the polarity of pre-recorded magnetization of a medium was investigated in perpendicular magnetic recording. Transitions are shifted toward the trailing direction, when the polarity of the head field is opposite to the one of leading magnetization. In contrary, they are shifted toward the leading direction, when the head field is the same polarity as the leading magnetization. In this paper, we confirmed that these phenomena affect the overwrite performance. We measured the distance of the transition shift in the overwrite recording and studied the relation between transition shifts and overwrite.

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  The error rate performance of PRML system in perpendicular magnetic recording by a multi-layered main-pole head is studied. First, the SNRs at the discrimination point are obtained for partial response (PR) systems whose taransfer functions are (1+D²)(1−D^m) (m = 1,2,···). Then, the bit-error rates of bit-gy-bit decoding exhibits teh best performance, ond that Viterbi decording and PMRL systems for these PR systems are obtained. The results show that among these PR systems PR(1,0,0,0,−1) system with bit-by-bit decoding for PR(1,0,1,0,−1,0,−1) system (PRML system) achieves a large improvement of SNR over bit-by-bit decoding.

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  An experimental high-speed magnetic recording channel at a 198Mb/s data rate for high definition digital VCRs was developed. An 8-12 convesion channel code with a density ratio of 1.33 was used. Optimum parameters of integration detection for the recoriding channel was considered, and then, the error rate below 10^-4 was measured. The paper also indicates a new decision method using 3 detection-levels at 2-bit interval.

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  The coercivity of CoCrTa hard disk media decreased to 1310 Oe from 1420 Oe with increasing time interval between substrate textureizing and sputtering from 10 minutes to 3 weeks. On the other hand, in the case of substrate kept in dry N₂ atomosphere, the decrease of coercivity was not observed even the time interval of 3 days.
  The contact angle of water for texturized substrate surface increased with the time interval.
  In XPS spectrum, it was observed large peaks originated by carbon compounds on the surface exposed in the air for long time interval.
  Therefore the decrease of coercivity is caused by the influence of the organic compounds adsorpted on the substrate surface.

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  Monoline process or integrated production system in hard disk fabrication was studied.
  Properties of hard disks depend on the time between processes because of alternating their surface conditions. In batch process, disks should be kept in a certain hours between processes untill the variation of surface conditions are saturated to avoid property deviations. In monoline process, disk properties will kept uniformly from disk to disk, because the periodical treatments give constant surface conditions. In some means, it should be called a dynamic process.

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  Computer simulation was carried out to clarify the thin film deposition process by sputtcring. In the simulation, the effect of the incident angles of the sputtered particles to the substrate surface on the structure of the deposited film was mainly investigated.
  The film structure depends strongly on the distribution of the incident angle of the sputtered particles. An increase in the amount of the incident particles with large incident angle leads to a formation of the films with a small density, rough surface and with a columnar structure. The oblique incidence of the sputtered perticles to the substrate also causes a remarkable reduction of the density of the film and a formation of an inclined columner structure. These results qualitatively agree with the experimental resnlts obtained in the deposition of CoCr films, which suggest that the control of the incident angle of the sputtered particle to the substrate is very important to obtain a desired film structure.

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  A magnetic circuit design by using a computer simulation has been performed, aiming at optimization of parameters for enhancing the magnetic field in the area of plasma formation. By the simulation, it becomes clear as follows: (a) The bottom thickness of the target is one of the most sensitive parameters. (b) The distance between the target bottom and the magnet placed beneath the target is also a sensitive parameter. (c) The effect of a return path formed with soft magnet irons around the target cannot be ignored. (d) The target permeability governs the field so strongly that a particular attention must be paid for high permeability materials to design an efficient magnetic circuits.

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  To fabricate a high performance double-layered medium, the underlayer should be satisfied not only good magnetic properties, but also good crystallinity and crystalline orientation in order to realize the homogenous and fine crystalline growth of Co-Cr recording layer. We have already proposed a new type target for a DC magnetron sputtering source to fabricate a tape medium continuously. The permalloy films sputtered by the new target show the good magnetic properties and crystallinity even at a high power. And so we investigate the application of this target to fabricating of the rigid disks. In this paper, we mention about the distribution of magnetic property of the Ni-Fe-Nb films sputtered by the new target, and examine the appropriate structure of this target.

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  Perpendicularly magnetized films of polycrystalline bismath substituted dysprosium iron garnets (Bi _xDy_3-xFe₅O₁₂, x=1.0 and 1.5) were attempted to prepare by spin-on process of a gel coated on glass substrates. The coated gels were preannealed at temperatures Tpa=400, 500 and 600 °C for 20 minutes to evacuate water, NO_x and hydrocarbon impurities contained in the gel. They were successively subject to heat treatment at temperatures Ta up to 800 °C for 4 hours to form garnet crystal. The experiment revealed that Tpa and the ramp rate to Ta govern the crystallographic nature of film. Single garnet phase films with good surface smoothness and finer grains were formed under the conditions that Tpa=400 °C and Ta=750 °C within a few minutes by employing a very high ramp rate anneal.

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  The change of saturation magnetostriction(λs), saturation magnetization(Bs), and soft magnetic properties(permeability μ' and coercivity Hc) were investigated for Co-based super structured films with Fe content up to 5at%.
  The films were prepared by using reactive RF sputtering method with N₂ gas periodically mixed into Ar gas. The ratio of N₂ gas partial pressure to the total gas pressure(η) was 20%, 26% and 33%. Thermal annealing of the films was performed at 515°C for an hour with a rotating magnetic fild applied in the film plane.
  Bs does not change within the experimental error whereas λs increases as the content of Fe increases and changes its sign from negative to positive. For the range of 86∼90at% of Co, |λs| of the films with 1∼2.5at% of Fe becomes less than 1×10^-5. The anisotropy of μ', namely, the ratio of μ' along the hard axis to that along the easy axis tends to increase with Fe content. This ratio for the films prepared with η =33% is greater than that for the prepared with η =20% and 26%.

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  α”-Fe₁₆N₂ with different lattice constants a and c were synthesized on MgO single crystal substrate under various fabrication conditions (total gas presure, deposition rate and N₂ flow ratio). Magnetic moment of α”-Fe₁₆N₂ compound films was discussed in connection with the change of the structural properties. As a result, no strong correlation was found between saturation magnetization, σ_s, and structural properties (1) degree of order of N atoms in b.c.t. Fe₁₆N₂ structure, (2) the magnitude of unit cell volume of α”-Fe₁₆N₂ and (3) the value of axial ratio of α”-Fe₁₆N₂.

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  In order to achieve high density recording, it is necessary to use a thin main-pole film. However, in thin film range, there is thickness-limitation for a single layer due to the domain structure. In comparison with that, multilayered films can be expected to disappear the closure domain because of its magnetostatic coupling. But the multilayered thin film heads often show instability in reproducing process. So we have to use the under layer between megnetic layer and substrate to control the stress in the films. As a result, we are able to accomplish high sensitivity and stable output in a thin film region less than 100nm.

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  In ordrer to achieve high linear density recording, a thin main-pole film for a single-pole head is indispensable. The authers investigated the soft magnetic properties and the domain structures of thin Fe-Si single-layered films and Fe-Si/SiO₂ multi-layered films. Good soft magnetic properties were obtained in both films. Contrary to this good magnetic properties, the single-layered main-pole film of 100nm thick showed unstable readback output and poor resolution. This poor head performance was closely related to the domain structure. On theother hand, the adoption of the multi-layered film controlled the domain structure and improved the high density response.

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  We have development a contact-single-pole-type-head. The head consists of a transducer and a suspention. We named the Head " Salanx Head ". The transducer has a double layer 40turn coil and a 6 μ m width pole R/W characeristics was measured and discussed.

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  Ultra-narrow track perpendicular magnetic recording of submicron track width was studied. Basic experiment for read/write performance showed that C/N ratio of low density single exceeds 30 dB, in addition, D₅₀ of 100 kFRPI is attainable by using a dedicated read head. The head field distribution of a single pole head causes this sharp track edge recording. The potential for nesrly 10 Gbytes disk drives with a 3.5 inch disk was estimated with this narrow track recording and inherent high linear density.

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  MIG (Metal in Gap) / TFC (Thin Film Coil) hybrid magnetic head by the combination of SCC (Side Core Composite) head and TFC, was developed in order to achive down-sizing and lowering the inductance of MIG head.
  TFC of hybrid head was developed by thin film techniques. By this technique we could eliminate the wire winding process which was one of the obstacles in down-sizing the MIG head.
  In this paper, the structure and electrical-magnetic characteristics of MIG/TFC hybrid magnetic head are discussed.

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  Co-Cr perpendicular magnetic recording media were fabricated by using an RF diode sputtering apparatus with applying DC bias voltage to substrate holder. As the DC bias voltage increases, perpendicular orientation of cobalt c-axis deteriorates, and perpendicular magnetic anisotropy decreases. At the proper bias voltage, high perpendicular coercivity is achieved by moderating the influence of impurity gas, and consequently the high reproduced voltage is obtained at high-densities.

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  Co-Cr films were prepared sputter-deposition at room temperature and at elevated Ar pressures up to 100 Pa which enables low voltage discharges. It was found by a SEM observation of the films that a dense fine structure at low Ar pressures changes to a large grained columnar structure with clear boundaries at Ar pressures of 10 to 50 Pa through a transition structure with smaller grain sizes. The grain size, however, decreases at higher Ar pressures more than 50 Pa disagreeing with the Thornton model. The grain size was reduced greatly by a Ti underlayer retaining the clear grain boundaries espcially for depositions at high Ar pressures. The crystal orientation and the deposition temperature might little affect the structure. It is concluded that the micro structure of the Co-Cr films with Ti underlayer deposited at high Ar pressures and at room tamperature have a fine and isolated columner structure, which may be one of the suitable structures for high density recorgding media.

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  Preparation of Ti films on glass disk substrates by sputter-deposition as underlayers for Co-Cr perpensicular magnetic recording media were investigated. The hcp c-axis orintation to the film normal of Co-Cr film became sharper by putting a highly orinted Ti underlayer for depositions at Ar pressures from 0.2 to 100Pa. It was found that Ti films deposited on glass disk substrates showed cryatal orientations with Δθ₅₀ greater than 7°, while films deposited on slide glasses showed high crystal orientations with Δθ₅₀ less than 5°. The Δθ₅₀ was decreased dramatically by a sputter-etching of the surface of the glass disk substrates prior to the deposition of the films.
  An XPS analysis reveraled that substantial Si atoms which didn't bond with oxigen were detected in the hetero interface for the non-processed glass substrates, but the concentration was redused by the sputter-etching of the substrate surface, It was suggested that the Si atoms degraded the crystal orientationl of the film.

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  The materials and its prepartion methods of backlayer for Co-Cr perpendicular magnetic recording media have been investigated. Multilayers composed of Ni-Fe layers and Co₆₇Cr₃₃ paramagnetic layers were proposed in order to satisfy the requirements of both the <111> axis orientation and excellent soft magnetism in Ni-Fe ferromagnetic layers. The multilayer revealed soft magnetic properties sufficiently as well as the good crystallinity and well <111> orientation suitable for the growth of Co-Cr crystallites with good c-axis orientation. Co-Zr-Ta thin films showed good soft magnetism with large saturation magnetization regardless of the film thickness. Ti interlayers between Co-Cr recording layers and Co-Zr-Ta backlayers were helpfull to achieve good c-axis orientation of Co-Cr crystallites which were deposited on it.

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  Experimental characterization of magnetic anisotropy and intergranular magnetic coupling for currently developed recording media was carried out with magnetic torque analysis. In thin film media, the magnitude of the magnetic fieled where rotational hysteresis loss vanishes showes an almost constant value in each meterial independent of coercive force H_c. It is concluded that this field nearly corresponds to magentic anisotropy field of grains. Experimental results shows that the increase of H_c in almost all thin film media is mainly caused by the decrease of the strength of intergranular exchange coupling. On the other hand, with decreasing the strength of intergranular coupling, the number of grains where Hc is determined by reversible rotation of magnetization gradually increases. Futhermore, the existence of incoherent magnetization reversal in grains is suggested in the real films especially in CoCrTa media.

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  I. Taganwa Y. Nakamura's method to measure a perameter ΔHc/Hc of anisotopy field distribution has been shown to be useful for its demagnetization correction free. In order to estimate the easy axis of obliquely oriented tapes, the angular dependence of the ΔHc/Hc in out-of-plane measurements was made for Hi-8 VCR ME (Metal-Evaporated) tape and obliquely oriented trial metal particle tapes. The easy axis direction in out-of-plane is estimated from the angular dependence of ΔHc/Hc without troublesome demagnetization correction. Particle disperaion and orientation ability of the magnetic paint is tried to estimate from the SQR ΔHc/Hc relations.

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  By investigating substitution effects on the properties of Ba ferrite particles for magnetic recording media, it has been found that Zn substituted particles have a rather small SFD(switching field distribution) compered with Co substituted particles. In particular, Co-Zn-Nb substituted Ba ferrite particles with a small amount of Co and a large amount of Zn are promising materials, exhibiting a small SFD and a small temperature coefficient of coercivity.
  The Zn-rich parricles have been found by torque measurement to be single-domain particles and have a uniaxial magnetocrystalline anisotropy not only at room temperature but also at low temperature. The Zn-rich particles have a small K₂ in comparison with K₁, while Co-rich particles have a comparatively large K₂, especially at low temperature. From these results, it can be said that the Zn-rich particles have an idial uniaxial magnetocrystalline anisotropy.
  By the measurement of rotational hysteresis integral and angular depedance of coercivity, it has been found that the magnetization reversal for a medium using the Zn-rich particles is incoherent but more coherent than for a medium using Co-rich particles.
  It has been found that recording media using the Zn-rich particles of Co-Zn-Nb substitution system exhibiting a small SFD show excellent recording performance, especially in a short wavelength range.

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  Tensile stress applied on a flexible thin film media was shown to be distributed on the thin metal layer and the polymer bese film in proportion to the product of thickness and elastic modulus. Depending on the relative thickness and modulus, a force applied on a tape in the usual VTR could exceed the yield point of the metal.

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  When a flexible magnetic medium is in contact with a magnetic head, Tribology, which is dependent on the mechanical properties of the medium, becomes a very impoportant issue. However, due to the thinness of the layer and the fact that it is attached to the substrate, these properties are very difficult to measure. This paper introduces a method for determining one of these properties of the magnetic layer -the Young's modulus.

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