Seagate has demonstrated the first terabit-per-square-inch hard drive, almost doubling the areal density found in modern hard drives. Initially this will result in 6TB 3.5-inch desktop drives and 2TB 2.5-inch laptop drives, but eventually Seagate is promising up to 60TB and 20TB respectively.
To achieve such a huge leap in density, Seagate had to use a technology called heat-assisted magnetic recording (HAMR). Basically, the main issue that governs hard drive density is the size of each magnetic “bit.” These can only be made so small until the magnetism of nearby bits affects them. With HAMR, “high density” magnetic compounds that can withstand further miniaturization are used.