Hard disk drive platter

This means that the magnetic domains cannot grow or shrink to form spikes, and therefore the transition width will be on the order of the diameter of the grains.

The coating has a complex layered structure consisting of various metallic (mostly non-magnetic) alloys as underlayers, optimized for the control of the crystallographic orientation and the grain size of the actual magnetic media layer on top of them, i.e. the film storing the bits of information.

[8] In post-processing a nanometer thin polymeric lubricant layer gets deposited on top of the sputtered structure by dipping the disk into a solvent solution, after which the disk is buffed by various processes [clarification needed] to eliminate small defects and verified by a special sensor on a flying head for absence of any remaining asperities or other defects (where the size of the bit given above roughly sets the scale for what constitutes a significant defect size).

In the hard-disk drive the hard-drive heads fly and move radially over the surface of the spinning platters to read or write the data.

Extreme smoothness, durability, and perfection of finish are required properties of a hard-disk platter.

[19][20][21] Toshiba followed suit with the MK1122FC in April 1991; their factories were able to produce many more drives than Areal, which soon disappeared from the market.

The reason for this transition is the need to continue the trend of increasing storage densities, with perpendicularly oriented media offering a more stable solution for a decreasing bit size.