38,497 research outputs found
Optical forces between dielectric nanoparticles in an optical vortex
We report a study on the optical forces between a pair of dielectric particles, based on quantum electrodynamics. At a fundamental level these forces result from a stimulated scattering process which entails a virtual photon relay between the two particles. Results for a variety of systems are secured from a completely general analysis that accommodates a system with arbitrary dielectric properties (with regard to shape, frequency response etc.) in an optical field of arbitrary complexity. Specific results are obtained and exhibited for: (a) optical forces between nanoparticles, and specifically between carbon nanotubes; (b) the effects of optical ordering, clustering and trapping associated with twisted (Laguerre-Gaussian) laser beams
Effects of atomic short-range order on the properties of perovskite alloys in their morphotropic phase boundary
The effects of atomic short-range order on the properties of
Pb(Zr_{1-x}Ti_x)O_3 alloy in its morphotropic phase boundary (MPB) are
predicted by combining first-principles-based methods and annealing techniques.
Clustering is found to lead to a compositional expansion of this boundary,
while the association of unlike atoms yields a contraction of this region.
Atomic short-range order can thus drastically affect properties of perovskite
alloys in their MPB, by inducing phase transitions. Microscopic mechanisms
responsible for these effects are revealed and discussed.Comment: 4 pages, with 2 postscript figures embedded. Uses REVTEX4 and
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