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Racetrack memory is an experimental memory that works by storing multiple magnetic regions called domains, similar to those on the surface of a hard disk, on a nanowire. Although there is no physical movement of the storage medium, the domains shift along the nanowire like horses along a racetrack.
In (a), the read line doesn't connect electrically to the nanowire; instead, it forms part of a magnetic tunnel junction — a spintronics device that combines a pulse of electricity with a magnetic reference layer to detect the movement of domains above it. Domains are injected by a pulse of electricity on the write line. Slides (b) and (c) show an actual cell close-up and with its surrounding electronics, while (d) and (e) are a 256-cell array at low and high magnification. For scale, the gold rectangles at the top of (d) are 80μm by 100μm.
Image credit: IBM