TEM & Computer Analysis of Crystallographic Orientation Ratio in [1120]-Co Films on [002]-Cr Films Grown on Mechanically Textured Substrates

Abstract

Circumferential mechanical texture (scratches) of hard drive substrates has improved head/media tribology; however, it has also been advantageous to the development of OR (Orientation Ratio) for longitudinal media. The magnetic dipoles prefer to circumferentially align with texture, which matches the direction heads read/write. The corrugated nature of films sputtered on fine texture scratches leads to an anisotropic stress state in the films, especially for those deposited at temperatures above ambient; and OR has been attributed to this anisotropic stress. A review article discusses possible causes of the OR such as: self-shadowing due to the texture lines during deposition, circumferential c-axis alignment, shape anisotropy of media grains, and magnetostrictive effects. Another work listed two requirements for OR: <> Co crystallographic growth texture in addition to circumferential texture scratches. The same study considered frequencies and depths of the texture scratches, and concluded that OR increased as the ratio of depth/frequency increased, rather than just as a function of Ra alone.