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Center for Nonlinear Studies |
On the proper timescale, amorphous solids can flow. Solid flow can be observed macroscopically in glaciers or lead pipes but, also, it can be artificially enhanced by creating defects. Ion Beam Sputtering (IBS) is a technique in which collimated ions with energies in the 0.1 to 10 keV range impact against a solid target inducing defect creation and dynamics, and eroding its surface leading to formation of ordered nano-patterns. Despite its technological interest, a basic understanding of the nanopattern formation processes occurring under IBS of amorphizable targets is still lacking: recent experiments having largely questioned knowledge accumulated during the last two decades. We consider that irradiated solids flow like incompressible highly viscous liquid. Properties of that liquid flow account for the complex IBS phase diagram, so that a non-erosive nature is unveiled for the morphological instability, as the interplay between incompressible fluid creep and ion-beam forcing. This new perspective can allow for a full experimental harnessing of this route to nanostructuring and opens new challenging problems on nano-wave formation, characterization and control. Although this work focus on modelling, it emphasizes the need of new experiments and Molecular Dynamics simulations.
Host: Ruy Ribiero