C. S. Mah

Influence of dual-Ru intermediate layers on magnetic properties and recording performance of CoCrPt–SiO2 perpendicular recording media

CoCrPt–SiO2 perpendicular recording media containing dual-Ru intermediate layers have been studied. The bottom Ru layer deposited under a higher mobility condition, i.e., low Ar gas pressure and bias on substrate, helps to achieve a good crystalline texture, and the top Ru layer under a lower mobility condition, i.e., high Ar gas pressure, promotes the formation of a columnar microstructure. Three kinds of grain boundaries have been observed. The nucleation field and the coercivity as a function of the thickness and dc bias of the bottom Ru layer have been investigated. Medium noise reduction has been observed for dual-Ru intermediate layer media (dual-Ru media) in comparison with that of single intermediate layer media (single-Ru media). This is mainly attributed to the optimization of the physical grain segregation.

Grain size reduction in CoCrPt:SiO2 perpendicular recording media with oxide-based intermediate layers

CoCrPt–SiO2 perpendicular recording media containing an oxide-based intermediate layer have been studied in order to minimize the grain size in the recording layer. A RuCr alloy thin film deposited in an argon and oxygen reactive atmosphere was found to produce finer grains in the intermediate layer. When the recording layer was deposited on such an intermediate layer, the grain size of the recording layer was also observed to be smaller (about 6.4nm center-to-center distances). The results indicate that the introduction of RuCr-oxide-based intermediate layers is a possible approach to reduce the grain size in perpendicular recording media.

Advanced perpendicular recording media structure with a magnetic intermediate layer

CoCrPt–SiO2 perpendicular recording media containing a CoCr-based magnetic layer as an intermediate layer was studied. CoCr film deposited on a growth control layer such as Ta could grow with a hcp[0002] out-of-plane orientation, which could induce the desired perpendicular easy-axis orientation for the CoCrPt:SiO2 magnetic layer. It was observed that the growth of an intermediate layer based on Ru between the magnetic intermediate layer and the magnetic recording layer is crucial to reduce the noise. Recording performance of disks with a magnetic intermediate layer was comparable or better than that of conventional perpendicular media indicating the potential of the proposed structure.

Palladium-based intermediate layers for CoCrPt–SiO2 perpendicular recording media

CoCrPt–SiO2 perpendicular recording media containing Pd and Ru based intermediate layers have been studied. A Pd thin film with a face-centered-cubic (fcc)[111] orientation perpendicular to the film plane can induce a Ru hexagonal close packed (hcp) [0002] perpendicular orientation, which can subsequently induce a vertical Co hcp [0002] orientation for the perpendicular recording. It was observed that certain growth control layers (GCLs), such as Ta and CrTi, help in improving the growth of Pd significantly with a fcc[111] orientation perpendicular to the film plane. With the addition of such layers, the full width at half maximum (Δθ50) of the rocking curves was reduced from more than 11° to about 4°. Moreover, with a CrTi GCL, the intermediate layer could be as thin as 15nm. Recording performance of disks with CrTi GCL was better than that of disks with Ta GCL. The results indicate that the identification of a suitable GCL for Pd is a path to reduce the Δθ50 further.

Role of substrate bias on the magnetic properties and microstructure of CoCrPt:SiO2 perpendicular recording media

The role of substrate bias during the sputter deposition of various layers of double-layered CoCrPt−SiO2 perpendicular recording media has been investigated in order to understand the physical mechanisms behind the various effects observed. Perpendicular recording media with dual Ru intermediate layers were investigated using several magnetic and microstructural characterization techniques. It was observed that, in general, the application of a bias voltage during the deposition of the seedlayer (Ta) and the first intermediate layer (Ru) is helpful in reducing the c-axis dispersion of the recording layer. For the other layers, application of bias voltage leads to deterioration in the magnetic properties. It was also observed that the application of a bias voltage during the deposition of the first intermediate layer (especially Ru) may not enhance the preferred growth of Ru hexagonal-close-packed (00.2) planes parallel to the disk surface, as predicted before. However, the bias voltage on the Ru layer sti...

CoCrPt–SiO

Co-alloy perpendicular recording media with a crystalline soft underlayer (c-SUL) is studied. Media with c-SUL can exhibit narrower c-axis dispersion with thinner intermediate layers and higher coercivity. On the other hand, c-SUL may show a higher noise, if not properly designed. We propose a stacked seedlayer design for the c-SUL. The noise can be reduced to the same level as that of amorphous soft underlayer (a-SUL)

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CoCrPt-SiO2-based perpendicular recording media with a thin intermediate layer and narrow c-axis dispersion of the grains in the magnetic layer were successfully prepared with a crystalline soft underlayer (c-SUL). The recording performance testing results show that media with c-SUL exhibit higher writeability than those on amorphous soft underlayer (a-SUL). The noise from c-SUL can be reduced to be lower than that from a-SUL

Perpendicular Recording Media With a Crystalline Soft Underlayer

In this paper, a crystalline soft underlayer with chemical formula (Fe₁₅Co₈₅)₉₄Cr₃Ta₃ for CoCrPt:SiO₂-based perpendicular media is studied. Three kinds of approaches are used to successfully reduce the noise from the soft underlayer. X-ray diffraction is used to study the effect of the preparation parameters on the orientations of the soft underlayer and the recording layer. The mechanism for the noise reduction is discussed

High Writability Perpendicular Recording Media With Low Noise Crystalline Soft Underlayer

This paper presents an alternative approach to reduce the grain size in recording media probably without affecting the anisotropy constant so much. It can be seen that the medium deposited on the new underlayers shows a smaller average grain size (6 nm) as well as a narrow grain size distribution (25%) as compared to 8 nm and 35% that is observed for the medium on conventional underlayer. The grain sizes are measured from center-to-center and the repoorted values include grain boundary as well.

Low-Noise Crystalline Soft Underlayer for CoCrPt:SiO

In this paper, we will describe a novel approach towards reducing the intermediate layer thickness in a non-physical way in perpendicular recording media. We use a magnetic material made of a CoCr alloy as one of the intermediate layers. Being a magnetic layer, this intermediate layer would be helpful during the writing process in passing the flux from head to SUL effectively. However, the challenges are obtaining a relatively low Deltathetas50 and a low noise. To test the concept, we have made films of the type Ta/CoCr/Ru/CoCrPt:Si02 on to AlMg disks coated with a soft magnetic underlayer. Synthetic antiferromagnetic intermediate layers of the type CoCr/Ru/CoCr where the individual CoCr layers are antiferromagnetically coupled to minimize any noise from the magnetic intermediate layers were also fabricated and studied.