Physicists pin down spin of sur...( Berkeley -- Scientists who dream of ...)

Berkeley -- Scientists who dream of shrinking computers to the nanoscale look to atomic spin as one possible building block for both processor and memory, yet setting the spin of an atom, let alone measuring it, has been a challenge.

Now, University of California, Berkeley, physicists have succeeded in measuring the spin of a single atom, moving one step closer to quantum computers and "spintronic" devices built from nanoscale transistors based on atomic spin.

"From a technical point of view, this demonstrates a new ability to engineer, fabricate and measure spin-polarized nanostructures at the single atom level," said Michael F. Crommie, UC Berkeley professor of physics. "Now that I can see an atom's spin, I can ask, 'What can I do with that atomic spin" Can I manipulate it" Can I use it, change it"' This means we can now start incorporating it into other structures."

Crommie and his colleagues at UC Berkeley and the Center for Computational Materials Science (CCMS) at the Naval Research Laboratory in Washington, D.C., recently reported their success in the journal Physical Review Letters.

At the core of today's digital computers are billions of tiny transistor circuits that, because they can exist in two states, are used to represent the binary digits, or "bits" 0 and 1, which are the basis of all computer manipulations.

As researchers seek to reduce the size of digital computers, they have been searching for nanoscale materials that can do digital duty, one of them being a single atom whose outer unpaired electron can be in either of two spin states - up or down.

While researchers previously have been able to deduce the spin polarization of an atom in a surface or thin film where the atoms are packed together and the spins are in an orderly arrangement, no one had been able to directly measure the polarization of an individual "adatom" spin until now. Adatoms are atoms that sit on top of a surface and are
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