Every few years experts proclaim the imminent end of advances in magnetic media, the technology behind most computer data storage. But engineers keep finding new tricks to cram more data onto hard drives, such as making the magnetic grains that store bits smaller. Now even these tactics are hitting a physical limit-but that doesn’t spell the end of magnetic media.

To keep increasing the data density of hard drives, researchers in a consortium that includes IBM and General Electric are working on a scheme called “patterned media,” which could boost storage capacity by physically isolating a disk’s magnetic grains from one another on nanoscale “islands.” In today’s technology, several hundred magnetic grains are needed to store a bit clearly, and if the grains become too small and densely packed, they lose their magnetic orientation. On an island, a bit might be stored stably with just one grain, allowing bits to be spaced more closely. A prototype device should be ready by 2004.

IBM has proved the concept by carving islands in magnetic alloys with a focused ion beam. And GE is developing a mass-manufacturing method, creating a polymer that can be stamped with a grid of pillars-each about 50 nanometers square and five nanometers high-and coated with a thin film of magnetic alloy. In their initial incarnation, patterned media could yield disks that hold between 30 and 40 gigabits per square centimeter, ten times the density of today’s products, says Brad Reitz, GE’s manager for the project. Eventually, says Bruce Terris, Reitz’s counterpart at IBM, the technology might be pushed to more than 150 gigabits per square centimeter. At today’s sizes, a laptop hard drive with that density could hold over a terabyte of data, and a device like Apple Computer’s iPod music player could hold more than 57,000 songs-almost 30 times its current capacity.

Other university and corporate labs are also pursuing patterned magnetic- media technology. But observers say these researchers shouldn’t count their terabytes until they’ve been tested. “Patterned media is very difficult to do,” says Dave Reinsel, a storage industry analyst for Framingham, MA-based IDC. “It’s a fundamental change to the way we do storage.” Nevertheless, Reinsel thinks patterned- media technology may make it out of the lab and onto the market by around 2008. If it does, magnetic storage may have an attractive future after all.