Racetrack memory
Schematic diagram of a racetrack memory: Binary data are stored in a U-shaped piece of nanowire in terms of two different magnetic domains (red and blue). According to IBM's Stuart Parkin, about 100 bits could be stored and retrieved from the memory by moving the sequence of domain walls past the read and write elements at the bottom of the U. This could be done using carefully-timed pulses of spin-polarized electrons, says Parkin (image courtesy: Mike Ross, IBM Almaden).