The dependence of the magnetic properties, crystallographic structure, morphological structure and recording characteristics on the angle of incidence were studied on the obliquely evaporated thin Co-O films. The preferred c-axis orientation angle of Co in Co-O films is almost equal to the minimum incident angle( e min), because the growth at the initial deposition stage around the maximum incident angle( emax) is very thin and has little magnetization due to oxidization. The Co-O film deposited at emin of 40· exhibits a maximum output at a recording density of 100kFCI, which is higher by 5dB than that of ME tape for a high-band 8mm VCR.

CoCrPt media with 20 nm thickness are fabricated at low temperatures on plastic disks using Cr and SiOz underlayers and on glass substrates using a Cr underlayer. The fabrication condition is optimized for high coercivity of 2.2 kOe on plastic and 2.4 kOe on glass. The dependence of magnetic properties on Ar pressure and sputtering power of CoCrPt is discussed for the media on plastic disks in comparison with the glass case, The micromagnetic properties such as Barkhausen volume and 6M are discussed. Recording properties of the media on plastic disks deposited under different fabrication conditions are also discussed, and are found to be consistent with micromagnetic properties.

Abstract---The inclinations of recorded magnetization of a Co-O :film and a Co-Ni-O :film deposited at the incident angles of 50~40· and 90~55· , respectively, against the normal to the :film plane are investigated by using the modified Bitter technique. For the Co-O :film and Co-Ni-O :film recorded at 2kFCI, the inclinations of magnetization from the :film plane are 20~30· and 20·, respectively. The inclination of recorded magnetization coincides with the effective easy magnetization direction on the either film.

TAIL-OFF RECORDING METHODA new recording method to improve the U N characteristics of the obliquely evaporated CO-COO tape was proposed.In this tail-off method, the recording current was cut for a certain period before applying the reverse current as shown in figure 1.CiN CHARACTERISTICS Fig. 2 shows the carrier signal output (C), the media noise (N) and the carrier-to-noise ratio (C/Nm) characteristics measured at h= 0.46 pm. Using the tail-off method, C increased by 2 dB and Nm decreased by 1 dB then C/Nm increased by 3 dB compared to the conventional method in this case under the M.M.F. (Magneto Motive Force) condition for maximum C output. Datasigns 0 1 0 1 0 0 0 1 1 Write c "~~" , "ltt-'"e -(bj Conventional NRZl Fig. 1 Write current diagrams of (a) tail-off and (b) conventional NRZl recording. INVEST GATIQN OF MECHANISM IN THE C / N M P R O V C To investigate the mechanism of ihCreaSe t P r e~~n t addms5 Tsukuba Research Labaralory, Himhi Maxell, Lld , Tsukubagun. Ibaraki. 300.24, Japan Fig 2 2 5 -1 0 0-7803-5555-5/99/$10.00 0 1 999 IEEE.in C output, remanence distributions were measured by VSM with applying field similar to real recording process [I]. Fig. 3 shows the comparison of its distribution between the tail-off and the conventional method. The increase in C should be explained by the suppression of demagnetization by head trailing edge field.We also investigated the influence of the field direction to micro-domain structure to understand the decrease in Nm in this tail-off method. Three types of remanent samples were prepared by applying the external field in longitudinal, normal and hard axis direction. Then their longitudinal and normal magnetization components were measured by the spin SEM equipped with a spin rotator [Z]. Fig. 4 shows the magnetization angle images reconstructed from these magnetization components.The narrowest width of the domain was obtained in case of applying field in hard axis direction. From these analysis we concluded that the decrease of Nm should be explained by the increase of the trailing edge fieid applied in hard axis that makes the width of domain narrower.

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