The high-speed, high-density hard drives in today's computers write information into spinning disks of magnetic materials, using electricity to toggle between magnetic polarity states that correspond to the "1" or "0" of binary computer code. But a number of intrinsic problems emerge with this method of data storage, notably limits to speed because of the spinning disk, which is made less reliable by moving parts, significant heat generation, and the considerable energy needed to write and read information.
Beyond that, magnetic storage suffers from a profound scaling issue. The magnetic fields in these devices exert influence on surrounding space, a so-called fringing field. Without appropriate space between magnetic data bits, this field can corrupt neighboring bits of digital information by inadvertently flipping "1" into "0." This translates to an ultimate limit on scalability, as these data bits need too much room to allow endless increases in data density.
One pioneering spintronic prototype is IBM's Racetrack memory, which uses spin-coherent electric current to move magnetic domains, or discrete data bits, along a permalloy wire about 200 nanometers across and 100 nanometers thick. The spin of these magnetic domains is altered as they pass over a read/write head, forming new data patterns that travel back and forth along the nanowire racetrack. This process not only yields the prized stability of flash memory devices, but also offers speed and capacity exceeding disk drives.
"It takes less energy to manipulate spin torque parameters than magnetic fields," said Pollard. "There's less
|Contact: Justin Eure|
DOE/Brookhaven National Laboratory