33,776 research outputs found
Metallic and semi-metallic <100> silicon nanowires
Silicon nanowires grown along the -direction with a bulk Si core are
studied with density functional calculations. Two surface reconstructions
prevail after exploration of a large fraction of the phase space of nanowire
reconstructions. Despite their energetical equivalence, one of the
reconstructions is found to be strongly metallic while the other one is
semi-metallic. This electronic-structure behavior is dictated by the particular
surface states of each reconstruction. These results imply that doping is not
required in order to obtain good conducting Si nanowires.Comment: 13 pages, 4 figures; Phys. Rev. Lett., in pres
Local rectification of heat flux
We present a chain-of-atoms model where heat is rectified, with different
fluxes from the hot to the cold baths located at the chain boundaries when the
temperature bias is reversed. The chain is homogeneous except for boundary
effects and a local modification of the interactions at one site, the
"impurity". The rectification mechanism is due here to the localized impurity,
the only asymmetrical element of the structure, apart from the externally
imposed temperature bias, and does not rely on putting in contact different
materials or other known mechanisms such as grading or long-range interactions.
The effect survives if all interaction forces are linear except the ones for
the impurity.Comment: 5 pages, 5 figure
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