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Nanowires show promise for atomic engines.
18:22 03 June 2005
Atomic
electromagnets made from coils of individual gold atoms could prove
valuable for nanocircuits and machines, a new study suggests.
Tomoya
Ono and Kinkuji Hirose at Osaka University in southern Japan performed
computer simulations to determine the electromagnetic properties of
helical gold
nanowires. These are rows of individual gold atoms twisted
around a central axis - like a wire spring - which measure 0.6
nanometres wide by 5 nm long.
The
calculations performed by Tomoya and Kinkuji were based on previous
experiments and observations of helical gold nanowires. They found that
the nanowires should generate a magnetic field as an electrical current
passes through the atoms, just as larger
conductive coils, known as
solenoids, do.
These
conductive coils are used in conventional electronic circuits or as
electromechanical actuators - used to generate a force. For example,
wrapping a coil around a ferromagnetic bar turns a regular solenoid
into an actuator that exerts a force on the bar when the current is
turned on.
Nanoscale friction
So
nano-solenoids could perhaps be used in super-efficient nanocircuits or
as part of a nanoscopic machine. "It''s not always immediately clear
what the applications may be," says John Mintmire, nanomaterials expert
at the Oklahoma State University, US. But he believes the wires could
conceivably find use as simple motors for nanoscopic machinery.
Mintmire,
however, notes that developing an atomic actuator could be fraught with
difficulties, since surface friction on the nanoscale would make
controlling such a tiny machine difficult.
"It''s not that it would be impossible," he told New Scientist." It''s just that the ground rules change on this scale."
Journal Reference: Physical Review Letters (DOI: 10.1103/PhysRevLett.94.206806)