Stars and stripes. Nanoscale misfit dislocation patterns on surfaces*
Raghani Pushpa and Shobhana Narasimhan
Theoretical Sciences Unit, Jawaharlal Nehru Centre
for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India
Abstract: Close-packed metal surfaces and heteroepitaxial systems
frequently display a structure consisting of regularly spaced misfit
dislocations, with a network of domain walls separating face-centered
cubic (fcc) and hexagonal close-packed (hcp) domains. These structures
can serve as templates for growing regularly spaced arrays of nanoislands.
We present a theoretical investigation of the factors controlling the
size and shape of the domains, using Pt(111) as a model system. Upon
varying the chemical potential, the surface structure changes from being
unreconstructed to the honeycomb, wavy triangles, "bright stars",
or Moiré patterns observed experimentally on Pt(111) and other
systems. For the particular case of Pt(111), isotropically contracted
star-like patterns are favored over uniaxially contracted stripes.
* Special Topic Issue on the Theme
of Nanostructured Advanced Materials
**Corresponding author
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