Tribology challenges for head-disk interface toward 1 Tb/in2

Achieving 1-Tb/in² magnetic recording areal density requires head-media spacing (HMS) to be no greater than 6.5 nm. It begs the question whether this is a reality (or physics)-based target. This paper examines the main functions and requirements of each HMS component, overcoats on media and head, lubricant film on media, and head-disk mechanical separation, to explore the feasibility of this 6.5-nm HMS budget. From the analysis one may conclude that, although extremely challenging and involving major paradigm shifts, this target does not appear to be completely out of bounds of physical limits. One HMS budget scenario has been proposed which allocates 1 nm each for disk overcoat, head overcoat, and disk lubricant film, leaving 3.5 nm for head-disk mechanical separation. Two fundamental strategies to achieve 3.5-nm head-disk mechanical separation were also discussed.