Microstructural origin of orientation ratio in magnetic recording media

We report x-ray-diffraction measurements of the microstructural origin of circumferential magnetic anisotropy [or orientation ratio (OR), the ratio of the remanent magnetization along the circumferential and radial directions] in textured magnetic recording disks. We study a series of CoPtCrB magnetic media with Cr X underlayers with varying OR and quantify the anisotropic strain in the Cr X underlayer and the c -axis alignment in the hexagonal-close-packed media. Our data show that the c -axis alignment results from the anisotropic strain in the underlayer and suggest that the OR comes predominately from the media c -axis alignment.