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NSF PR 00-09 - March 21, 2000
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Physicists Produce "Left-Handed" Composite Materials
Physicists supported by the National Science Foundation
(NSF) have produced a new class of composite materials
with physical properties that scientists theorized
might be possible, but had never before been produced.
The materials are called "left-handed" because they
reverse many of the physical properties observed in
ordinary materials in response to electromagnetic
Lead scientists Sheldon Schultz and David Smith of
the University of California at San Diego will announce
their findings today at a meeting of the American
Physical Society in Minneapolis, Minn. and publish
them in a future issue of Physical Review Letters.
The new class of materials has the ability to reverse
properties such as the Doppler effect, the principle
that changes the frequency of waves as the source
of the waves moves. Thus, a train whistle sounds higher
in pitch as the train approaches and lower as the
train recedes. Maxwell's equations, which describe
the relationship between magnetic and electric fields,
suggest that microwave radiation or light would show
the opposite effect in this new class of materials,
shifting to lower frequencies as the source approaches.
Similarly, Maxwell's equations suggest that a lens
made of such materials, instead of dispersing electromagnetic
radiation as usual, would focus it as it passes through.
"If these effects turn out to be possible at optical
frequencies, this material would have the crazy property
that a flashlight shining on a slab can focus the
light at a point on the other side," said Schultz.
The scientists demonstrated the ability to reverse
these properties by beaming microwave radiation through
a composite material produced from a series of thin
copper rings and ordinary copper wire strung parallel
to the rings. Their results verified the composite
had negative electric permittivity and negative magnetic
permeability. In most known materials in nature, these
qualities are positive.
The composite created by the team is among a new class
of materials called "metamaterials," in which the
way two or more materials are mixed, or arranged,
at a very fine level can affect the electromagnetic
properties of the resulting composite.
Ultimately, the development of this new class of left-handed
metamaterials, which was financed by NSF and the Department
of Energy, could have applications in areas such as
microwave transmissions, antennae design, and optical