Ill. (June 11, 2004) — Researchers from the U.S. Department
of Energy's Argonne National Laboratory and Northern
Illinois University have shown that very thin materials
can still retain an electric polarization, opening
the potential for a wide range of tiny devices.
The researchers found that the ferroelectric phase
– the ability to hold a switchable electric polarization
– is stable for thicknesses as small as 1.2 nanometers,
one-billionth of a meter, or a size several hundred
thousand times smaller than the period at the end
of this sentence.
Previous studies had found that, as the material became
too thin, it quit being a ferroelectric. These new
results, however, suggest that small thicknesses do
not pose a fundamental problem to building very small
devices based on these materials. The research is
published in the June 11 issue of Science magazine.
“The natural ordering of the atoms in their crystal
structure cause these materials to be electrically
polarized,” said researcher Carol Thompson of NIU.
“This means that, in the jargon of the scientists,
these ferroelectric materials exhibit rich and complex
couplings between their optical, chemical, mechanical,
structural and thermal properties. Alterations of
the natural structure due to size and surface effects
will perhaps destroy their ability to perform as ferroelectrics.
However, we will be relying on these materials to
behave themselves. Will they? The research suggests
that they will behave better than we had any right
to expect before.”
An increasingly wide range of applications are based
on ferroelectric thin films, including sensors, microelectromechanical
systems and memory systems. Studies of ferroelectrics
have become more intense in recent years, as devices
– and the materials and thin films used to manufacture
them – have become smaller, moving to the micro- and
even the nano-scale, creating machines and building
blocks of electronic devices smaller than the width
of a human hair. The technological potential of these
materials depends on maintaining a stable ferroelectric
phase as devices continue to be miniaturized.
The researchers used the powerful X-ray beams from
the Advanced Photon Source at Argonne – the nation's
most brilliant X-rays – to monitor the electric transition
in thin films as they are grown, layer by layer.
Argonne is building a new Center for Nanoscale Materials
that will provide enhanced capability to fabricate
and study novel materials and devices at the nanoscale.
The authors are D.D. Fong, G.B. Stephenson, S.K. Streiffer,
J.A. Eastman, Orlando Auciello and P.H. Fuoss of Argonne
and Carol Thompson of NIU. Funding is provided by
the Office of Basic Energy Sciences, part of the Department
of Energy's Office of Science, and by the State of
The nation’s first national laboratory, Argonne National
Laboratory conducts basic and applied scientific research
across a wide spectrum of disciplines, ranging from
high-energy physics to climatology and biotechnology.
Since 1990, Argonne has worked with more than 600
companies and numerous federal agencies and other
organizations to help advance America's scientific
leadership and prepare the nation for the future.
Argonne is operated by the University of Chicago for
the U.S. Department of Energy's Office of Science.
For more information, please contact Catherine Foster
(630/252-5580 or email@example.com) at Argonne or Joe
King (815/753-4299 or firstname.lastname@example.org) at Northern