03-05-2012, 02:25 PM
RACETRACK MEMORY
Racetrack memory is an experimental non-volatile memory device under development at IBM's Almaden Research Center by a team led by Stuart Parkin. It is one of a number of new technologies trying to become a universal memory in the future.
Fundamental concept of Racetrack memory is to store multiple data bits per access point, rather than typical single bit per transistor. It is accomplished by storing data bits in the form of domain walls in magnetic nanowires. Racetrack memory uses a spin-coherent electric current to move magnetic domains along a nanoscopic permalloy wire. As current is passed through the wire, the domains pass by magnetic read/write heads positioned near the wire, which alter the domains to record patterns of bits. A racetrack memory device is made up of many such wires and read/write elements. Racetrack memory uses electrical currents to "push" a magnetic pattern through a substrate.
Dramatic improvements in magnetic detection capabilities, based on the development of spintronic magneto-resistive sensing materials and devices, allow the use of much smaller magnetic domains to provide far higher areal densities. The simplest is a series of flat wires arranged in a grid with read and write heads arranged nearby. A more widely studied arrangement uses U-shaped wires arranged vertically over a grid of read/write heads on an underlying substrate.