Dafiné Ravelosona, an experimental physicist at the Institute of Fundamental Electronics in Orsay, France, leads a European collaboration working on its own version of racetrack memory. He says IBM’s latest results are a crucial step along the road to commercialization for the technology. “It’s a nice demonstration that shows it’s possible to make this kind of memory using CMOS,” he says.
However, Ravelosona adds that the IBM work doesn’t yet demonstrate all of the key components that make racetrack memory desirable. “They have only demonstrated that it is possible to move a single bit in each nanowire,” he explains.
Much of the promise of the technology lies in the potential to store many bits—using many magnetic stripes—in a single tiny nanowire, to achieve very dense data storage. Ravelosona suggests that the material used to make the nanowires in the new IBM device lacks the right magnetic properties to allow that.
Parkin says that the intention wasn’t to target density but adds, “We’re focusing on exactly this question.” His group is currently working on how to fit as many magnetic stripes as possible into a nanowire and has begun experiments that suggest that wires made from a different type of material may do better.
The nickel-iron alloy of the integrated prototype is what’s known as a soft magnetic material, because it can be easily magnetized and demagnetized by an external magnetic field. Parkin is also experimenting with hard magnetic materials, which get their magnetic properties from their tightly fixed crystalline structure and as a result are not easily demagnetized.
“Using this different material, we have discovered we can move the domain walls [between magnetic stripes] very fast and that they are much smaller and stronger than in the soft magnetic material used in the integrated devices,” says Parkin.
That means not only that it should be easier to put many stripes into one nanowire, but also that nanowires fabricated with less precision will still work, which should make fabrication easier. “I call this racetrack 2.0,” he says.