Argonne scientists discover new class of glassy
material
Dynamic frustration may lead to better understanding
of glass in nature
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ARGONNE, Ill. (July 28, 2008)–Scientists at U.S. Department of Energy's
Argonne National Laboratory are dealing with an entirely new type of frustration,
but it's not stressing them out. Dynamic frustration has been found to be
the cause of glassy behavior in materials that previously had none of the features
of a normal glass.
Funding for this research was provided by the U.S. Department of Energy, Office
of Science, Office of Basic
Energy Sciences. The mission of the Basic Energy Sciences (BES) program
-- a multipurpose, scientific research effort -- is to foster and support
fundamental research to expand the scientific foundations for new and
improved energy technologies and for understanding and mitigating the
environmental impacts of energy use. |
This discovery may allow scientists to tune the degree of frustration and
therefore develop a better understanding of how glasses are formed in nature.
"This has been a puzzle for 10 years now," Argonne physicist Raymond
Osborn said.
Conventional wisdom states that glassy materials, such as common window glass,
result when frustration prevents the atoms from forming a well ordered crystal
structure, and the material freezes into a disordered state like a frozen liquid.
In spin glasses, the magnetic moments on each atom, rather than the atoms
themselves, freeze into a disordered state at low temperatures, so they point
in random directions. However, there has to be some disorder in the atomic
structure and some frustration in the magnetic interactions to prevent the
magnetic moments from ordering so they can freeze into spin glasses.
Scientists have struggled for more than a decade to understand why PrAu2Si2 (a compound of praseodymium, gold and silicon) is a spin glass. There
is no sign of atomic disorder in the compound and no reason for the magnetic
interactions to be frustrated.
Using the results of neutron scattering experiments, Osborn and his collaborators
concluded the frustration results from temporal or dynamic frustration rather
than static frustration.
Although PrAu2Si2 seems to have an ordered structure,
by delving deeper, Osborn found that the magnetic moments are continually fluctuating
in magnitude causing the equivalent of temporal potholes that appear and then
disappear long enough to disrupt the magnetic alignment.
These fluctuations occur because the magnetic moments in this material are
unstable and can be destroyed temporarily by electrons scattering off the atoms.
"The discovery of dynamic frustration reveals a whole new class of glassy
materials whose behavior is governed by dynamic rather than static disorder," Osborn
said.
Funding for this research was provided by the U.S. Department of Energy, Office
of Science, Office of Basic
Energy Sciences. The mission of the Basic Energy
Sciences (BES) program -- a multipurpose, scientific research effort -- is
to foster and support fundamental research to expand the scientific foundations
for new and improved energy technologies and for understanding and mitigating
the environmental impacts of energy use.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology.
The nation's first national laboratory, Argonne conducts leading-edge basic
and applied scientific research in virtually every scientific discipline. Argonne
researchers work closely with researchers from hundreds of companies, universities,
and federal, state and municipal agencies to help them solve their specific
problems, advance America 's scientific leadership and prepare the nation for
a better future. With employees from more than 60 nations, Argonne is managed
by UChicago
Argonne, LLC for
the U.S.
Department of Energy's Office
of Science.
For more information, please
contact Brock Cooper (630/252-5565 or media@anl.gov)
at Argonne.
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