Perpendicular Magnetic Recording Media on Various Hard-Disk Substrates
Co-Cr perpendicular media on rigid substrates were studied. We used untextured glass substrates for perpendicular magnetic hard disks, but the reproduced output at short wavelengths was influenced by the surface roughness of the magnetic recording media. We therefore fabricated Co-Cr perpendicular hard disk media deposited onto different substrates: untextured glass, silicon single crystal, chemically textured alumite, and Mn-Zn ferrite. We compared these substrates with respect to their crystallographic properties, head-to-medium spacing, and record/playback characteristics.
Spin alignment of surface oxidized CoxNi1–x/Cu(001)
We investigated the ferromagnetic (FM)/antiferromagnetic (AF) spin alignment of a 13 monolayer oxidized CoxNi1–x/Cu(001) (x = 0 or 0.05) surface by X-ray magnetic circular dichroism and X-ray magnetic linear dichroism photoemission electron microscopy (XMCD-PEEM and XMLD-PEEM). Surface NiO and the underlying Ni (CoxNi1–x) were found to be AF and FM by analyzing the gray scale of XMLD-PEEM and XMCD-PEEM images; this indicates the spin orientation with respect to the polarization of the incident X-ray. We found both collinear and perpendicular alignment of the FM and AF spins. This suggests that the AF NiO is magnetically random, resulting in coercivity enhancement without exchange bias in the surface-oxidized CoxNi1–x/Cu(001) films.
The effect of texturizing on the magnetic and recording properties of plated rigid disks
Texturizing of rigid disk surfaces is used to reduce the area of contact between the head and the disk, and thus reduce the stiction and friction forces in contact start-stop applications. In this study, we investigated the effects of circumferential texturizing on the magnetic properties, the recording performance, and the noise of thin film disks prepared by electroless chemical deposition. Regarding the magnetic properties, we found that texturizing results in a small increase in the squareness and the coercivity and in a much larger reduction in the switching field distribution of the films. These magnetic effects contribute a 5-10% improvement in signal at densities of 10-20 kfci (400-800 fc/mm). Media modulation noise is unaffected by texturizing for film thicknesses in the range of 60-80 nm. For smaller thicknesses, texturizing seems to contribute some incremental noise, while for larger thicknesses the reverse is observed. The main source of noise in these media, however, arises from the zig-zag domain patterns in the magnetization transition regions which have their primary origin in the exchange coupling between the crystallites.