Seagate claims it has achieved the milestone storage density of 1 terabit (1 trillion bits) per square inch, using the heat-assisted magnetic recording technology, which promises to double the storage capacity of today's hard drives.

The technology, which is not expected to be find its way to hard disk drives anytime soon, may give rise to 3.5-inch hard drives with an extraordinary capacity of up to 60 terabytes over the 10 years that follow, according to Seagate.

The current hard drive technology, Perpendicular Magnetic Recording (PMR), is used to record the spectrum of digitized data on the spinning platters inside every hard drive. PMR technology was introduced in 2006 to replace longitudinal recording, a method in place since the advent of hard drives for computer storage in 1956, and is expected to reach its capacity limit near 1 terabit per square inch in the next few years.

Hard drive manufacturers increase areal density and capacity by shrinking a platter's data bits to pack more within each square inch of disk space. They also tighten the data tracks, the concentric circles on the disk's surface that anchor the bits. The key to areal density gains is to do both without disruptions to the bits' magnetization, a phenomenon that can garble data. Using the Heat-assisted Magnetic Recording (HAMR) technology, Seagate has achieved a linear bit density of about 2 million bits per inch, resulting in a data density of just over 1 trillion bits, or 1 terabit, per square inch - 55 percent higher than today's areal density ceiling of 620 gigabits per square inch.

The maximum capacity of today?s 3.5-inch hard drives is 3 terabytes (TB), at about 620 gigabits per square inch, while 2.5-inch drives top out at 750 gigabytes (GB), or roughly 500 gigabits per square inch. The first generation of HAMR drives, at just over 1 terabit per square inch, will likely more than double these capacities - to 6TB for 3.5-inch drives and 2TB for 2.5-inch models. The technology offers a scale of capacity growth never before possible, with a theoretical areal density limit ranging from 5 to 10 terabits per square inch - 30TB to 60TB for 3.5-inch drives and 10TB to 20TB for 2.5-inch drives.

Seagate achieved these data density breakthroughs in materials science and near-field optics at its heads and media research and development centers in Bloomington, Minnesota, and Fremont, California.