Superinsulators promise to transform materials research, electronics design|
Posted on Monday, April 07, 2008 @ 21:54:22 EDT by vlad
Newly discovered 'superinsulators' promise to transform materials research, electronics design
Superinsulation may sound like a marketing gimmick for a drafty attic or winter coat. But it is actually a newly discovered fundamental state of matter created by scientists at the U.S. Department of Energy's Argonne National Laboratory in collaboration with several European institutions. This discovery opens new directions of inquiry in condensed matter physics and breaks ground for a new generation of microelectronics.
Led by Argonne senior
scientist Valerii Vinokur and Russian scientist Tatyana Baturina, an
international team of scientists from Argonne, Germany, Russia and
Belgium fashioned a thin film of titanium nitride which they then
chilled to near absolute zero. When they tried to pass a current
through the material, the researchers noticed that its resistance
suddenly increased by a factor of 100,000 once the temperature dropped
below a certain threshold. The same sudden change also occurred when
the researchers decreased the external magnetic field.
Like superconductors, which
have applications in many different areas of physics, from accelerators
to magnetic-levitation (maglev) trains to MRI machines, superinsulators
could eventually find their way into a number of products, including
circuits, sensors and battery shields.
If, for example, a battery is left exposed to the air, the charge
will eventually drain from it in a matter of days or weeks because the
air is not a perfect insulator, according to Vinokur. "If you pass a
current through a superconductor, then it will carry the current
forever; conversely, if you have a superinsulator, then it will hold a
charge forever," he said.
"Titanium nitride films, as
well as films prepared from some other materials, can be either
superconductors or insulators depending on the thickness of the film,"
Vinokur said. "If you take the film which is just on the insulating
side of the transition and decrease the temperature or magnetic field,
then the film all of a sudden becomes a superinsulator."
Scientists could eventually form superinsulators that would
encapsulate superconducting wires, creating an optimally efficient
electrical pathway with almost no energy lost as heat. A miniature
version of these superinsulated superconducting wires could find their
way into more efficient electrical circuits.
Titanium nitride's sudden transition to a superinsulator occurs
because the electrons in the material join together in twosomes called
Cooper pairs. When these Cooper pairs of electrons join together in
long chains, they enable the unrestricted motion of electrons and the
easy flow of current, creating a superconductor. In superinsulators,
however, the Cooper pairs stay separate from each other, forming
"In superinsulators, Cooper pairs avoid each other, creating
enormous electric forces that oppose penetration of the current into
the material," Vinokur said. "It's exactly the opposite of the
superconductor," he added.
The theory behind the experiment stemmed from Argonne's Materials
Theory Institute, which Vinokur organized six years ago in the
laboratory's Materials Science Division. The MTI hosts a handful of
visiting scholars from around the world to perform cutting-edge
research on the most pressing questions in condensed matter physics.
Upon completion of their tenure at Argonne, these scientists return to
their home institutions but continue to collaborate on the joint
projects. The MTI attracts the world's best condensed matter
scientists, including Russian "experimental star" Tatyana Baturina,
who, according to Vinokur, "became a driving force in our work on
Scientists from the Institute of Semiconductor Physics in
Novosibirsk, Russia, Regensburg and Bochum universities in Germany and
Interuniversity Microelectronics Centre in Leuven, Belgium, also
participated in the research.
The research appears in the April 3 issue of Nature.
Source: Argonne National Laboratory
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