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Capturing Atomic Spirals

Defect structures serve as nucleation sources that allow growth and evolution of structure at temperatures far lower than perfect crystalline structure would allow. Screw dislocations, which form spiral growth/etch patterns when they evolve freely on a thin film surface, are the classical example of this behavior. Nanoscalecrystalline structures provide a mechanism for capturing the spiraling dislocation within the boundaries of thenanostructure. Such a trapped trapped structure no longer can spiral freely, and instead develops a periodic structure with a highly non-uniform angular frequency. Very simple physical phenomena -the free energy of a curved interface, and the Brownian motion of atoms at the dislocation edge, suffice to model the behavior quantitatively.


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Copyright (2007) University of Maryland, College Park. All rights reserved. Permission to redistribute the contents without alteration is granted to educational institutions for non-profit administrative or educational purposes with proper citation of the literature reference and with credit given to the NSF-MRSEC at the University of Maryland, College Park as the source.