31 March 2006

Solitons Observed In A Solid

by Kate Melville

An international team of researchers say they have observed evidence of solitary vibrations (solitons) in a solid. The scientists, from Los Alamos, Oak Ridge and Argonne laboratories, and the Institute for Transuranium Elements in Germany, write about their discovery of random localized vibrations in a three dimensional solid in Physical Review Letters.

The Scottish scientist John Scott Russell first described the soliton in 1834 after observing the phenomenon on the surface of a canal while conducting experiments to determine the most efficient design for canal boats. Twenty years ago, scientists theorized that solitons might exist in solids but physical evidence of their existence was lacking.

Now however, the researchers have used x-ray and neutron scattering experiments to identify random localized vibrations - called lattice solitons - in uranium crystals at high temperatures. They speculate that the vibrations are caused by strong electron-phonon interactions.

Los Alamos's Michael Manley said the results were exciting on several levels. "Although the idea of a localized energy wave goes back to the late 1800s when solitons were first observed, by the 1980s new theories proposed the possibility of seeing them in discrete solids. Scientists have been looking for localized vibrations in atomic structures ever since. No one ever imagined that they would play such an important role in the physical properties of uranium metal, so this was quite a surprise," he explained.

The discovery will have immediate implications for uranium science and solid-state physics and other potential applications will likely emerge in the future. Interestingly, the study noted that the localized vibrations may play a role in breaking chemical bonds in biological processes.

Source: Los Alamos National Laboratory