Entropy and error: density limit for magnetic data storage

Magnetic data storage is pervasive in the preservation of digital information and the rapid pace of computer development requires ever more capacity. Increasing the storage density for magnetic hard disk drives requires a reduced bit size, previously thought to be limited by the thermal stability of the constituent magnetic grains. The limiting storage density in magnetic recording is investigated treating the writing of bits as a thermodynamic process. A ’thermal writability’ factor is introduced and it is shown that storage densities will be limited to 15 to 20 TBit/in unless technology can move beyond the currently available write field magnitudes.