A team of Duke
University engineers has
created a master “ingredient list” describing the properties of more
than 2,000 compounds that might be combined to create the next generation of
quantum electronics devices.
The goal is topological insulators (TI), man-made crystals
that are able to conduct electrical current on their surfaces, while acting as
insulators throughout the interior of the crystal. Discovering TIs has become
of great interest to scientists, but because of the lack of a rational
blueprint for creating them, researchers have had to rely on trial-and-error
approaches, with limited success to date.
Because of their unique properties, TIs can be created that conduct
electricity more efficiently while also being much smaller that conventional
wires or devices. They are ideal candidates to become quantum electronics
devices, the Duke researchers said.
The “key” developed by the Duke investigators is a
mathematical formulation that unlocks the data stored in a database of
potential TI ingredients. It provides specific recipes for searching for TIs
with the desired properties.
In November, Stefano Curtarolo, professor of mechanical
engineering and materials sciences and physics at Duke’s Pratt School of
Engineering and founder of the Duke’s Center for Materials Genomics, and
colleagues reported the establishment of a materials genome repository which
allows scientists to stop using trial-and-error methods in the search for
The project developed by the Duke engineers covers thousands
of compounds, and provides detailed recipes for creating the most efficient
combinations for a particular purpose, much like hardware stores mix different
colors of paint to achieve the desired result. The project is the keystone of
the newly formed Duke’s Center for Materials Genomics.
“While extremely helpful and important, a database is
intrinsically a sterile repository of information, without a soul and without life.
We need to find the materials’ ‘genes,'” said Curtarolo. “We have
developed what we call the ‘topological descriptor,’ that when applied to the
database can provide the directions for producing crystals with desired
While developing the key to this database, the team also
discovered a new class of systems that could not have been anticipated without
such a “genetic” approach.
The Duke research was reported online in Nature Materials.
The new descriptor developed by the Duke team basically can
determine status of any specific combination of element under investigation. On
one end of the spectrum, Curtarolo explained, is “fragile.”
“We can rule those combinations out because, what good
is a new type of crystal if it would be too difficult to grow, or if grown,
would not likely survive?” Curtarolo said. A second group of combinations
would be a middle group termed “feasible.”
But what excites Curtarolo most are those combinations found
to be “robust.” These crystals are stable and can be easily and
efficiently produced. Just as importantly, these crystals can be grown in
different directions, which gives them the advantage of tailored electrical
properties by simple growth processes.
While TIs are currently in the experimental stage, Curtarolo
believes that with this new tool, scientists should have a powerful framework
for engineering a wide variety of them.
Source: Duke University