Thin films of CoPtCr and CoPtCr–SiO2, perpendicular magnetic media materials, were investigated by synchrotron radiation grazing-incidence x-ray diffraction. The analysis of diffraction peaks in a reciprocal space provided the variation of stacking faults as functions of Pt content in these materials. It was found that stacking faults start increasing at 15–20 and 25–30at.% Pt for CoPtCr–SiO2 and CoPtCr films, respectively. These results can well explain the phenomenon whereby the magnetic anisotropy of CoPtCr–SiO2 increases with an increasing Pt content and decreases above 20at.% Pt, whereas that of CoPtCr increases up to 30at.% Pt and then decreases.

A CoPtCr-SiO2 film is a potential material for high-density perpendicular recording media due to their high magnetic anisotropy constant Ku. However, the value of Ku decreases in high levels of Pt content. In this study, this phenomenon was analyzed by synchrotron radiation grazing incidence x-ray diffraction and transmission electron microscopy techniques. Although the CoPtCr-SiO2 films contained almost no fcc phase at 20at.% Pt or less, it increased remarkably at 30at.% Pt. This result coincided with the variations of Ku with respect to the Pt content for the CoPtCr-SiO2 films. We consider that the fcc phase formation at Pt content levels in the vicinity of 30at.% is an influential factor of the Ku reduction. Our techniques proved to be sensitive for the detection of fcc regions in the CoPtCr-SiO2 films.

Switching field distributions (SFDs), are presented for longitudinal media of ∼40 Gbit/in.2 and the influence of thermal agitation of magnetization is discussed. Two remanence curves were measured at different sweep rates of applied field of ∼10 and ∼108 Oe/s, respectively, and SFD curves were obtained by differentiating the remanence curves. The SFD becomes significantly narrower at the higher field sweep rate. A SFD curve without the effect of thermal agitation was calculated using Sharrock’s equation. The full width at half maximum of the SFD curve at 10 Oe/s, ΔHr/Hr, is 0.45 for an isotropic medium, while that estimated without the thermal agitation effect ΔH0/H0 is 0.24, indicating that the SFD at the recording frequency is nearly half that measured at vibrating sample magnetometer (VSM) time scales. The ΔH0/H0 of the ∼40 Gbit/in.2 medium is much smaller than that of a 15 Gbit/in.2 medium used for comparison, although the ΔHr/Hr is ∼1.4 times larger than that of the 15 Gbit/in.2 medium due to thermal agitation. The value of ΔH0/H0 is not influenced by the uniaxial anisotropy induced by substrate texture KuTX. This result indicates that the KuTX is not effective for reducing SFD at recording frequencies, although the KuTX strongly affects the SFD at VSM times scales. The improvement of recording performance with increasing KuTX may be related to suppression of thermal relaxation of the remanent magnetization at bit transitions, immediately after the writing process.

In this study, we investigated surface features formed by molten KOH etching of (000-1) substrates and epilayers, using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (TEM). We found the surface features formed on (000-1) are protrusions, in contrast to well-known dimples on (0001).

The magnetic printing method, which can duplicate soft magnetic patterns containing digital information such as servosignals formed on a master disk onto recording media, enables signals to be written to hard-disk media having high coercivities above 6000 Oe. We propose the application of the magnetic printing method to a hard-disk medium having double recording layers, one layer of which has high coercivity and is to be printed with digital information. This double recording layer medium is a hard-disk medium that has a magnetic read-only-memory (MROM) layer. In this study, we demonstrated a method for printing to this medium, which has MROM, and discussed the magnetic properties and recording performances of this medium.