Spintronics doctors create more spin

Spintronics may sound like a science practiced by political spin doctors. But spintronics-or spin electronics-is actually a growing branch of electronics in which the spin of electrons is manipulated in a magnetic field to allow for information storage. Electrons rotate in one of two directions, up or down.

A magnetic field can be used to exploit and control the spins, and information is written in the Os and ls of digital language by assigning a value to an up or down spin. The spinning electrons attach themselves to mobile electrons and are carried along a wire and read at a terminal. Laptops have gotten smaller, and today's computer hard drives hold more than 100 gigabytes of memory because of spintronics. The read heads in computers are now all giant magnetoresistive (GMR) sandwich structures, constructed of alternating ferromagnetics and nonmagnetic metal layers. As a hard drive spins, magnetized areas flip the electrons in the read head to transmit data. These read heads can detect weak magnetic fields, a process that allows for smaller bits of data.

Scientists are now working to create spintronic semiconductors. But Sankar Das Sarma, director of the Condensed Matter Theory Center at the University of Maryland, says "semiconductor spintronics, where spin plays an active role, is still a research subject and has not gone into any use, but there are many novel ideas which may eventually allow semiconductor memories to do processing and storage on the same chip." M-- RAM, or magnetic random access memory, would use the same technology, only putting magnetic sandwiches on a chip stitched with wires through which an electric current flows that can flip the spinning electrons to either up or down. The amount of electricity used in M-RAM is minute, which means it requires less power that today's chips. Once M-- RAM is perfected for commercial use, all of today's chip-enabled devices, from cell phones to personal digital assistants, will gain enormous amounts of memory storage capacity Das Sarma says the delay in releasing M-RAM commercial products comes from unanticipated fabrication and manufacturing problems, which should soon be solved. "IBM is working hard on the manufacturing problems," he says. And, if the industry spin doctors are right, the first M-RAM computers should be available in about two years.