This paper has touched briefly on the remarkable historical
progress of magnetic recording and of hard disk drive technology.
The recent spurt of rapid progress has been brought about by the
introduction of perpendicular magnetic recording together with
very sensitive TMR sensors as well as slider-based thermal-
actuation that enables precise control of head-medium spacing
down to very low clearance. It is the author’s opinion that such
rapid progress is unlikely to continue into the next decade
because of fundamental limits on the physics underlying the
technology. We should expect demand to outstrip areal-density
growth over the next few years and cost and sheer drive capacity
to be at a premium compared to other performance measures.
Good engineering and continued improvements in writer design,
head-media spacing, reader-sensitivity, track-following accuracy,
and signal processing will undoubtedly push us close to these
limits. In particular, media thermal stability is the source of this
fundamental limitation on areal density. There is some hope that a
‘conventional’ medium designed with properties cleverly graded
through its thickness may allow a finely grained medium to be
created that is both thermally stable and still ‘writable’. Beyond
conventional recording lies a fork in the road where critical
decisions need to be made between ‘patterned media’ and ‘energy
assist’—two very different and very challenging routes to the
future of storage technology.