Perpendicular Magnetic Recording Tape Research Articles

Effect of doubly layered Ru intermediate layers in perpendicular magnetic recording tape media

Si/NiFe bilayer structures are very effective to obtain c-axis orientation in both a Ru intermediate layer and a CoPtCr-SiO2 recording layer when they successively deposited on the Si/NiFe bilayer. Doubly layered Ru which consists of two Ru layers prepared at low and high sputtering gas pressures promoted c-axis orientation and well-isolated grains of the CoPtCr even when the Ru intermediate layer was very thin. Doubly layered Ru intermediate layers deposited on Si/NiFe seed layers attained suitable c-axis orientation and well-isolated grains of the CoPtCr recording layer, even though the Ru double-layer was as thin as 5 nm.

Reducing media noise of perpendicular magnetic recording tape for over-50 TB class data cartridge

To reduce medium noise inherent in a perpendicular magnetic recording tape, which is deposited by facing targets sputtering, we have examined an epitaxial double-layered structure consisting of a soft magnetic underlayer (SUL), bcc-FeCoB/fcc-NiFe/Si/bcc-FeCoB, on a 4.5 μm para-aromatic polyamide (aramid) film. An epitaxial soft magnetic bilayer reduces broadband noise by 5.6 dB at 337 kilo fluxchanges per inch (kfci) compared to a single SUL medium (Tape S). This is due to the reduction in the low-frequency noise, which originates from the domain walls of the SUL. Improvement of the crystal orientation of the magnetic layer hcp-CoPtCr–SiO2 and the intermediate layer hcp-Ru by inserting a fcc-NiFe spacer in laminated SULs extends the roll-off curve toward high linear density. When each SUL layer of the bilayer was made thinner, from 25 nm (Tape D2) to 10 nm (Tape D1), the medium noise decreased, improving the signal-to-noise ratio by 8.6 dB at 337 kfci compared to Tape S. In a high resolution playback test of Tape D1, an areal density of 45.0 gigabits per square inch (Gb/in.2) was confirmed. Achieved areal density means the capability of an over-50 terabyte (TB) capacity for a typical linear-formatted data cartridge.

Effect of laminated crystalline FeCoB soft magnetic underlayer for perpendicular magnetic recording tape media

A crystalline FeCoB soft magnetic underlayer (SUL) improves c-axis orientations of the Ru intermediate layer (IML) and the CoPtCr-SiO2 recording layer (RL). (001) orientations of Ru IML and CoPtCr RL are attained by (110) oriented texture of FeCoB SUL. Since good c-axis orientation in CoPtCr-SiO2 RL as well as domain control in the FeCoB SUL is required for high recording density, a laminated FeCoB SUL is prepared as an underlayer of the bilayered Ru/CoPtCr–SiO2 films. A laminated FeCoB SUL results in better (001) orientation in both CoPtCr-SiO2 RL and Ru IML than the single layered FeCoB SUL. This leads to the reduction of media noise in the high recording frequency region. Recording medium layers composed of a laminated FeCoB SUL and bilayered Ru/CoPtCr-SiO2 films deposited on a 4.5-μm-thick Aramid tape show better (001) orientations of Ru and CoPtCr. Media noise of the tape medium with the laminated SUL is lower than that with the single layered FeCoB SUL.

Fabrication of perpendicular magnetic recording tape media with a data capacity of over-50TB using Si/NiFe/FeCoB soft magnetic underlayers

C-axis orientations of Ru intermediate layer (IML) and CoPtCr-SiO2 recording layer (RL) are attained by using crystalline FeCoB soft magnetic underlayer (SUL). Better (110) orientation of FeCo improves not only (001) orientation of Ru IML but also that of CoPtCr RL. This leads better perpendicular magnetic anisotropy in the RL suitable for perpendicular magnetic recording media. In order to control the (110) orientation in FeCoB layer, various seed layers are prepared beneath the FeCoB layers. Ru and Si/NiFe seed layers gives FeCoB layer a large in-plane magnetic anisotropy that is effective to suppress spike noise from SUL. The laminated FeCoB SUL causes more improvement of Ru (001) texure and leads to better perpendicular magnetic anisotropy of RL. Ru/CoPtCr-SiO2 bilayer deposited on laminated FeCoB SUL on Aramid tape substrate has good perpendicular magnetic properties and reduces the noise from SUL. PACS: Type pacs here, separated by semicolons;

Playback performance of perpendicular magnetic recording tape media for over-50-TB cartridge by facing targets sputtering method

Perpendicular magnetic recording tape medium with laminated soft magnetic underlayers was successively formed on a 4.5 μm thin plastic film by the facing targets sputtering method at room temperature. The tape medium showed extremely high SNR values with sharp transitions in playback tests by a drum tester, compared to a linear format commercial tape medium. An areal density of 45.0 Gb/in. 2 of perpendicular tape medium was confirmed by a high-resolution contact tester. These results suggest that the perpendicular recording tape medium by the facing targets sputtering method is a promising candidate for a tape cartridge of over 50-TB.

Large output and high density recording tape with perpendicular magnetic Co–Cr–Ta film for VCR

In order to prepare the perpendicular magnetic recording tape, a small amount of Ta was added into the Co–Cr films and Kr was used instead of Ar as a sputtering gas. The recording and reproducing characteristics of the Co–Cr–Ta tape were evaluated using a one-half inch VCR. The reproduced output at the recording wavelength of 0.33 μm was 56 nVO-P/(μm T m/s). This value was almost equal to the reproduced output of MP tape at the recording wavelength of 0.66 μm.

Prospect of 1 T bits/in 3 video data storage using perpendicular magnetic recording tape

Future trends for high-density video data storage of 1 T bits/in 3 in multimedia service are discussed in this paper. A magnetic recording tape with CoCrTa/NiFe multilayer has been prepared using a facing targets sputtering system. Read/write characteristics and digital video recording characteristics of this tape have been investigated using a modified conventional VCR. It has been proven that the tape should be highly efficient in high-density recording of 1 T bits/in 3.

The read/write characteristics of Co-Cr-Ta/Ni-Fe double-layer tape for digital video recording

A digital video recording experiment was conducted by using a Co-Cr-Ta/Ni-Fe double-layer perpendicular magnetic recording tape and ring heads with a track width of 5 μm. The area recording density was 1.1bit/μm2, almost 8 times that of the D-3 VTR. A new equalizing method using FFT analysis was also developed for the experiment, achieving a byte error rate of 1×10-5.

Preparation of Co-Cr alloy/Ni-Zn ferrite double-layered films for perpendicular magnetic tape

Co-Cr alloy/Ni-Zn ferrite double-layered films for perpendicular magnetic recording tape are proposed to improve high frequency characteristics, and their preparation is described. The films were deposited by the Ferrite Plating method which enables to synthesize the soft magnetic spinel ferrite layers at low temperatures below 100/spl deg/C and by the facing targets sputtering (FTS) for the Co-Cr layers. It was found that the Co-Cr layers need to compensate the tensile internal stress of 1.0-1.5/spl times/10/sup 9/ dyn/cm/sup 2/ in the ferrite plated backlayers to avoid curling of the tape and to improve adhesion of the backlayers to substrates, and Ar pressure of 0.2-0.3 mTorr in the FTS was proper for depositing the Co-Cr layers with the optimum compressive stress and the excellent crystallinity.

Preparation of CoCrTa films for high-density magnetic recording tape

A perpendicular magnetic recording tape for ultrahigh density recording requires a high H c, a high H k and a small Δ H c/ H c. Furthermore for use in video tape recorders (VTR), mechanical properties such as reduction in tape curling and optimization of tape stiffness are important. In this study the effect of Ta added to CoCr film and Kr sputtering gas were examined. In addition, CoCrTa thin film media, suitable for VTR tapes, were prepared using a facing targets sputtering (FTS) system.

Improvement of anisotropy of perpendicular magnetic recording tape by Ta addition and Kr sputtering gas (abstract)

A perpendicular magnetic recording tape requires a high magnetic anisotropy field Hk and a small distribution of the perpendicular magnetic anisotropy field σhk/Hk. It can be expected that by the extension of the interplane distance of (002) plane d(002) in Co-Cr, a perpendicular magnetic anisotropy energy will be increased and Hk becomes higher. It can be also expected that the σhk/Hk becomes smaller by the improvement of the crystallinity of Co-Cr film. Therefore, in order to achieve the above, the following experiments were attempted. At first, a small amount of Ta was added to Co-Cr. This, as a result, extended the d(002) of the Co-Cr from 2.033 to 2.046 Å. Consequently, Hk was increased from 4.4 to 5.1 kOe and σhk/Hk was reduced from 0.14 to 0.11. Second, as a sputtering gas, Kr gas was used instead of Ar gas. The use of Kr resulted in greater crystallinity in the film, increasing the peak intensity I(002) of x-ray diffraction of the Co-Cr-Ta from 2090 to 2500 cps. Consequently, σhk/Hk was reduced up to 0.07. Last, a recording and reproducing experiment with the Co-Cr-Ta tape was attempted with the use of a hilical-scan VTR machine. As a result, a reproduced output of 56 nVO-P (μm T m/s) was obtained at the recording wavelength of 0.33 μm. This figure is equivalent to the output at the recording wavelength of 0.66 μm of metal-powder tape.

Continuous fabrication of Co-Cr perpendicular magnetic recording tape

To achieve high-throughput fabrication of Co-Cr/Ni-Fe double-layer perpendicular media, the optimum conditions for continuous preparation and construction of a new dc magnetron sputtering target have been investigated with respect to the aperture shield mask position and the magnetic circuit. The perpendicular magnetic tape media fabricated in a roll-coater equipped with the improved target showed high reproduced voltage at high densities.

Recording Characteristics of Co-Cr-Ta Perpendicular Magnetic Recording Tape at Short Wavelength

Recording Characteristics of Co-Cr-Ta Perpendicular Magnetic Recording Tape at Short Wavelength

Perpendicular magnetic recording tape suitable for ring head

Application of perpendicular magnetic recording technology is requisite in order to realize a next generation digital VCR whose recording density is about 1 bit/ μm2 . Since ring heads are considered to be used for the digital VCR, tapes must be suitable for the ring heads and digital signal. The tape with tilted easy axis is one of the candidates, which has single-peak-like isolated reproduced waveform, has lower spacing loss factor than that of the tape with non-tilted easy axis, and has high reproduced voltage not only in high linear density region but in low density region.

Continuous formation of CoCr films on PEN tape by facing targets sputtering

In order to establish the technique of continuous formation of Co-Cr film on PEN (polyethylene naphthalate) tape, the sputtering and deposition area in the facing-targets sputtering (FTS) system was divided into two areas. In the first area, an initial underlayer as thin as 200 AA with a well-oriented c-axis was formed. In the second area, a main layer as thick as 1500 AA was formed on the initial underlayer at a rate of 500 AA/min; good c-axis orientation facilitated epitaxial growth. It was found that the FTS method can suppress the c-axis canting of the Co-Cr crystallites without a significant increase of total deposition time. Thermoplastic PEN tape can be used without heat damage, instead of the heat-resistant polyimide, as a substrate for Co-Cr films for the perpendicular magnetic recording tape. >

Dynamic Properties of Perpendicular Magnetic Recording Tape Coated with Acicular Ba-Ferrite Media

Magnetic properties of a particulate film fabricated from acicular Ba-ferrite microparticles, coated onto a plastic tape, were evaluated. Squareness ratio measurements showed that this fine dispersion of particles in paint 1) was clearly oriented in the direction of their easy magnetization axis after orientation in a magnetic field, 2) is much more readily formed into a coating film than hexagonal-plate-form Ba-ferrite particles, and 3) has a smooth magnetic field orientation. The hysteresis measurements showed that acicular Ba-ferrite particles have an excellent perpendicular magnetic anisotropy.

Co-Cr perpendicular magnetic recording tape by vacuum deposition

The relation between the incident angle and the crystallographic orientation of a vacuum deposited Co-Cr film is discussed. Also presented are the magnetic properties and the orientation of both a Ni-Fe underlayer and the Co-Cr film for the double layer medium, and the experimental results about the composition distribution in the co-cr film. The films were deposited on a transporting polymer substrate by continuous vacuum deposition. It is found that the orientation of the Co-Cr film is determined only by the incident angle at the initial point of the film formation, and that deposition efficiency more than 50% can be achieved easily. A double layer medium with Ti film under the Ni-Fe film (Co-Cr/Ni-Fe/Ti medium), which is suitable for perpendicular magnetic recording, is produced by vacuum deposition. Auger depth profile in radial direction of the column of the Co-Cr film shows directly that there is Cr segregation near the columnar grain boundaries.