When designing an embedded system choosing which tools to use often comes down to building a custom solution or buying off-the-shelf tools.
TR10: Racetrack Memory
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This simple design has the potential to combine the best qualities of other memory technologies while avoiding their drawbacks. Because racetrack memory stores data in vertical nanowires, it can theoretically pack 100 times as much data into the same area as a flash-chip transistor, and at the same cost. There are no mechanical parts, so it could prove more reliable than a hard drive. Racetrack memory is fast, like the dynamic random-access memory (DRAM) used to hold frequently accessed data in computers, yet it can store information even when the power is off. This is because no atoms are moved in the process of reading and writing data, eliminating wear on the wire.
Just as flash memory ushered in ultrasmall devices that can hold thousands of songs, pictures, and other types of data, racetrack promises to lead to whole new categories of electronics. "An even denser, smaller memory could make computers more compact and more energy efficient," Parkin says. Moreover, chips with huge data capacity could be shrunk to the size of a speck of dust and sprinkled about the environment in tiny sensors or implanted in patients to log vital signs.
When Parkin first proposed racetrack memory, in 2003, "people thought it was a great idea that would never work," he says. Before last April, no one had been able to shift the magnetic domains along the wire without disturbing their orientations. However, in a paper published that month in Science, Parkin's team showed that a spin-polarized current would preserve the original magnetic pattern.
The Science paper proved that the concept of racetrack memory is sound, although at the time, the researchers had moved only three bits of data down a nanowire. Last December, Parkin's team successfully moved six bits along the wire. He hopes to reach 10 bits soon, which he says would make racetrack memory competitive with flash storage. If his team can manage 100 bits, racetrack could replace hard drives.
Parkin has already found that the trick to increasing the number of bits a wire can handle is to precisely control its diameter: the narrower and more uniform the wire, the more bits it can hold. Another challenge will be to find the best material for the job: it needs to be one that can survive the manufacturing process and one that allows the magnetic domains to move quickly along the wire, with the least amount of electrical current possible.
If the design proves successful, racetrack memory could replace all other forms of memory, and Parkin will bolster his status as a magnetic-memory genius. After all, his work on giant magnetoresistance, which led to today's high-capacity hard drives, transformed the computing industry. With racetrack memory, Parkin could revamp computing once more.