Friday, September 17, 2004

"CHIPS:IBM taps spintronics to reset molecular memories"
IBM Corp.'s progress in characterizing the magnetic spin of individual atoms and in flipping them from "up" to "down" could lead to molecular-cascade memories, a new type of memory chip that would pack a bit of data in every atom. IBM Fellow Don Eigler's group at Almaden Research Center (San Jose, Calif.) recently demonstrated IBM's new nanoscale characterization method, dubbed "spin-flip spectroscopy." To study how to switch the spin of individual atoms, IBM constructed a new type of measuring device. It combines a scanning tunneling microscope with a superconducting coil providing a high-strength magnetic field. The whole machine is supercooled to near-absolute zero. "We invented spin-flip spectroscopy so that we can study how to use magnetic spin for information storage, because at IBM our ultimate goal is the ultimate memory density possible � storing bits on individual atoms," said Andreas Heinrich, a researcher in Eigler's lab. "For instance, we demonstrated our molecular-cascade memories two years ago, but at that time we didn't have a way to reset them � they just fell over like dominoes, then we had to pick them back up one by one. Now we think we can use magnetism to reset a future version of molecular cascades." Eigler and Heinrich performed the work with IBM researcher Christopher Lutz and Jay Gupta, an assistant professor at Ohio State University. With the machine, IBM was able to characterize the precise amount of energy required to flip the spin of an atom from up to down � which is usually encoded to mean "1" and "0." The result was 0.0005 electron-volts, some 10,000 times less than the energy of a single molecular bond.