High-density Longitudinal Recording Media Research Articles

High-density longitudinal recording media with CrMoB underlayer

The structural, magnetic, and recording properties of longitudinal recording media with CrMoB underlayer were studied and compared to those with CrMo underlayer. Media with CrMoB underlayer have smaller grain size, better grain segregation, lower coercivity, and better recording performance than media with CrMo underlayer.

Activation volume and correlation to media noise in high-density longitudinal recording media

The activation volume (V/sub a/) and its correlation to media noise in high-density longitudinal recording media are investigated. Magnetization decay is observed to be non-linear with ln(t) for the media studied, and the necessity for using a correct method for estimating a fluctuation field is emphasized. The activation volumes are shown to increase with decreasing reversing fields and the values of V/sub a/ at low fields (of a few hundred Oe) are significantly higher than those at the coercivity. Thus, the collective behavior of the magnetic grains is influenced not only by the intergranular interactions but also by the stray fields. The media noise of different media is correlated to the V/sub a/ values at low fields.

Magnetic Force Microscopy Analysis of Thermal Stability in Longitudinal Media

AbstractThe thermal stability of written bits in high density longitudinal recording media is investigated using magnetic force microscopy (MFM). The time dependence of the MFM signal is examined for different linear densities on CoCrPt-based media of various thickness. At ambient temperature, lesser decay is observed using the MFM compared to spin stand measurements on the same CoCrPtTaNb media on Al which emphasizes the dependence of bit stability with writing conditions. Moderate anneals at 373 K reveal a rapid initial ∼ 10% signal decay followed by stable behavior not observed in the magnetization time dependence measurements. 200 kfci tracks on a 20-nim thick CoCrPtTa medium on Si with a coercivity of 3 kOe displayed stable (∼ 2%) behavior against a 105-hour anneal at 373 K in air. These results are correlated with media properties to obtain parameters that are good indicators of thermal stability performance.

Textured Growth of Strontium Ferrite Thin Films by Sputtering

Study of M-type hexagonal ferrite films (BaFe 12 O 19 and SrFe 12 O 19 ) is drawing a lot of interest due to their potential applications. Ba ferrite films with perpendicular anisotropy have been studied due to their projected use in perpendicular recording media, magneto-optic recording media and in microwave/millimeter wave devices. The current interest in depositing these films with in plane anisotropy is for use in high density longitudinal recording media. There have been attempts to deposit these materials, mostly on crystalline substrates though without complete control over the orientation. We have for the first time deposited the sputtered strontium ferrite films and could vary the texture of the film to obtain both perpendicular and in plane anisotropy. It was found that the films prepared at lower rf power when annealed at temperatures ≥ 800 °C showed perpendicular anisotropy while the films prepared with higher rf power after similar annealing showed in plane anisotropy. These films had been prepared without substrate heating during sputter deposition and the as deposited films were X-ray amorphous and were nonmagnetic. However, these 'as deposited' films when annealed, showed different textures depending on the deposition conditions, as if these deposition conditions leave some signature in the films, which eventually decides the texture of these films. The microstructural studies showed that though the 'as deposited' films were X-ray amorphous, oriented microcrystallites form during deposition, which could be controlling the texture at the time of complete crystallization during annealing.

ＳｉＯ２添加によるＣｏＮｉＰｔ磁性膜の微視的構造制御

The microstructural and magnetic properties of CoNiPt alloy films :with SiO2 added were studied to determine the films' potential for use in high-density longitudinal recording media. The Si in the sputtered film is in the form of SiO2 and is segregated at the grain-boundary. With the addition of the SiO2, the grain size becomes smaller and grain separation becomes well developed. These changes in the grain structure are attributed to the presence of segregated SiO2.The in-plane coercivity increases and media noise decreases significantly with an increase of SiO2, while the crystal orientation dose not change. A magnetic ripple structure indicating the clustering of exchange-coupled grains fades out with the addition of the SiO2. Thus, the well-developed grain separation due to the addition of SiO2 is responsible for the excellent magnetic properties, which are suitable for high-density recording media.