IBM is developing a new type of ultra-low-cost solid-state memory featuring a storage
capacity that vastly exceeds what today's hard disk drives can provide. Called racetrack memory, the technology may one day replace hard disk drives in PCs, laptops and servers as well as displace flash memory chips in smartphones, digital cameras, and tablets.
The radically new type of storage memory is based on a breakthrough technology known as spintronics, which manipulates the two types of independent electrons found in electrical current -- called the "spin-up" and "spin-down" electrons. The goal is to enable computing devices to store bits of information by manipulating the magnetic state of a region within a nanowire that is just a few tens of nanometers wide.
"We discovered that domain walls don't hit peak acceleration as soon as the current is turned on -- it takes them exactly the same time and distance to hit peak acceleration as it does to decelerate and eventually come to a stop," said IBM Research Fellow Dr. Stuart Parkin on Thursday. "Now we know domain walls can be positioned precisely along the racetrack simply by varying the length of the current pulses, even though the walls have mass."
Astounding Memory Capacities
Conventional hard disk drives remain popular because they are cheap, but the technology is also slow, prone to read/write errors, and can suffer irreversible damage if dropped or hit. Though solid-state memory chips are superfast and far more reliable, they also cost about 100 times more per gigabyte of memory than hard disk counterparts.
Nanowire racetrack technology promises to bring the benefits of solid-state construction to PC and server memory storage without a comparable boost in cost, IBM researchers observed. Even mobile handheld devices may one day ship with astounding amounts of storage memory, they added.
By sliding magnetic bits of information back and forth along the nanowire racetrack, computing devices can read changes to the magnetic states of the domain walls. Despite moving at speeds in the hundreds of miles per hour, they also can be commanded to stop precisely at the position needed. As a result, computing devices will be able to access massive amounts of stored information in less than a billionth of a second, IBM researchers said.
A Year's Worth of Movies
Big Blue's goal is to boost device storage capacities by a factor of 100 times greater that what is currently available today from conventional memory devices. This would enable hardware makers to design portable gadgets capable of storing all the movies produced worldwide in a single year -- and with room to spare, IBM researchers said.
To make such memory densities possible, however, the domain walls of the nanowire racetrack must be manipulated at speeds of hundreds of miles per hour to atomically precise positions along the tracks. According to IBM researchers, the timescales in the tens of nanoseconds and the distances in micrometers are surprisingly long, given that research efforts over the past 50 years were unable to detect them.
"This was previously undiscovered in part because it was not clear whether the domain walls actually had mass, and how the effects of acceleration and deceleration could exactly compensate one another," Parkin said.
IBM researchers have just published their results in the Dec. 24 issue of Science. The paper by Luc Thomas, Rai Moriya, Charles Rettner, and Stuart Parkin of IBM Research is entitled, "Dynamics of magnetic domain walls under their own inertia."