IBM researchers are now a step closer to commercialising an experimental technology that could be used load up a mobile phone with so much storage that it could keep copies of every movie made this year.
Called "racetrack memory," it's a technology that IBM Fellow Stuart Parkin has been tinkering with since 2004. Unlike a hard drive, which spins magnetically charged atoms around using a motor, racetrack memory uses electric currents to move collections of electrons, called magnetic domain walls, up and down a very tiny wire. "It's like a kind of magnetic wave that we're moving along without having to move the atoms," Parkin said.
By moving these domain walls to a reader, racetrack should be able to read and write data much more quickly, and using far less power than today's storage devices. "It would be a million times faster to access the first bit, and use much less energy, and there would be no problem with crashes," Parkin said.
Parkin thinks he can have a big effect on the storage capacity of common electronic devices such as phones. With the right funding, he thinks he's two to five years away from building chips filled with minuscule wires were he could push magnetic domains around, storing up to one hundred times as much data as today's flash memory chips. Using wires a few microns long and about 30 nanometers wide -- one thousandth the thickness of human hair -- the first racetrack chips could store hundreds of gigabytes or even a few terabytes of data, Parkin said.
Parkin's team has already developed some early racetrack prototypes -- chips that can read and write simple data sets -- but until now there was a key unanswered question: How exactly do these magnetic domain walls move? "If we wanted to manipulate and place these domain walls precisely, that was something we needed to know," Parkin said.
Before now, there had been two schools of thought on this question. One held that the magnetic waves that Parkin talked about had no mass and would move instantly at their set speed as soon as the current was applied; and they'd stop instantly too. The other view was that maybe they actually had mass and were subject to the laws of inertia -- taking a bit of time to speed up to speeds of hundreds of miles per hour, and essentially coasting to a stop when the current was turned off.
In a paper published in the Dec. 24 issue of Science Magazine, the IBM researchers report that domain walls have mass and do indeed take a bit of time to speed up to peak velocity, and to slow down. Knowing this, they'll be able to move and retrieve data on a racetrack trip accurately.
There's still a lot of work to be done before racetrack becomes a reality, but according to Parkin, the biggest questions -- whether an electric charge would move these domain walls, and whether or not they have mass -- have now been answered.
Now the problems are more practical and less theoretical: how do you build a racetrack chip that works reliably with millions or even billions of these racetracks, for example. "Those are the questions that we can only address by building prototypes and testing them for a period of time," Parkin said.