Atomic-level Computing

IBM reported yesterday that its scientists have developed a new technique for exploring and controlling magnetism at the atomic level. The breakthrough could lead to the development of new materials for computing devices based on microscopic magnetic phenomena.

"We have developed a window into the atomic heart of magnetism," said Andreas Heinrich, a research staff member at IBM's Almaden Research Center in San Jose, Calif. "We can now position atoms and then measure and control their magnetic interactions within precisely designed structures."

The technique, called spin-excitation spectroscopy, uses a low-temperature scanning tunneling microscope to probe the interactions between spins in individual atomic-scale magnetic structures. The researchers created linear chains of 1 to 10 manganese atoms assembled one atom at a time on a thin insulating layer, and the spin excitation spectra of these structures were measured with inelastic tunneling spectroscopy. They observed excitations of the coupled atomic spins that can change both the total spin and its orientation. Comparison with a model spin interaction yielded the collective spin configuration and the strength of the coupling between the atomic spins. They found that chains with an even number of atoms had no net magnetism, while chains with an odd number of atoms showed net magnetism, according to the IBM announcement.

"This kind of exploratory research is essential for the long-term future of the computer industry," said Gian-Luca Bona, manager of science and technology at the Almaden center. "Sometime in the next couple of decades, it will be impossibly difficult to continue improving transistors and other traditional microelectronic circuit elements by simply shrinking them. We will then need alternative structures and, perhaps, altogether different ways of computing. Techniques like this can help us gain the knowledge needed to create those alternatives."

IBM said its scientists expect to use spin-excitation spectroscopy to:

  • 'Explore the limits of magnetic data storage, by engineering the energy required to flip the collective orientation of a small number of magnetically coupled atoms.'

  • 'Determine the feasibility of spin-based wires and a spin version of the molecular-motion cascade.'

  • 'Investigate how engineered spin interactions could be applied to quantum information systems, such as quantum computers.'

More information on spin-excitation spectroscopy is available at IBM's Web site and at the online publication Science Express.

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