Electronic Surface Melting
Crystals melt through one of two processes: surface melting, or surface freezing. In the first, the surface melts at a lower temperature than the bulk, resulting in a liquid layer at the surface (a phenomenon believed to help skiers slide across the snow). In the second, the bulk melts first, resulting in a crystalline layer floating on a liquid. So, what happens if the order that is melting is not atomic crystalline order, but rather electronic order? Using surface x-ray scattering techniques, researchers at Brookhaven and Argonne National Laboratories have shown that for at least one case, electronic order exhibits surface melting – that is the electronic surface melts before the bulk. The researchers showed that for orbital order in a manganite, close to, but below the bulk electronic melting temperature, the orbital surface held melted, while the bulk remained ordered – electronic surface melting. This result has important implications for future electronic devices which require well-defined electronic interfaces, and may be a particular issue for nanoscaled devices which are dominated by their surface behavior.
The work will appear in the 15 October 2011 issue of Physical Review B, where it is an Editor’s Suggestion: S. B. Wilkins et al., Phys. Rev. B. 84 165103 (2011).
This work was supported by the U.S. Department of Energy Office of Science.