- Number 369 |
- August 13, 2012
Unprecedented subatomic details of exotic ferroelectric nanomaterials
Direct polarization images of individual
ferroelectric nano cubes.
As scientists learn to manipulate little-understood nanoscale materials, they are laying the foundation for a future of more compact, efficient, and innovative devices. Adding to the toolbox to advance that goal, scientists at DOE’s Brookhaven and Lawrence Berkeley labs and collaborating institutions have developed a new technique that allows them to image individual atoms and associated electric fields in exotic ferroelectric materials. The technique reveals unprecedented details about the atomic structure and behavior of these materials, which are uniquely equipped to store digital information and could usher in a new generation of advanced electronics.
The technique, called electron holography, captures images of the electric fields created by the materials’ atomic displacement with picometer precision. By applying different levels of electricity and adjusting the temperature of the samples, researchers demonstrated a method for identifying and describing the behavior and stability of ferroelectrics at the smallest-ever scale.
“This kind of fundamental insight is not only a technical milestone, but it also opens up new engineering possibilities,” said Brookhaven physicist Yimei Zhu.
Current magnetic memory devices, such as the hard drives in most computers, “write” information into ferromagnetic materials by flipping their intrinsic magnetic dipole moment to correspond with the 1 or 0 of a computer’s binary code. Those manipulated polarities then translate into everything from movies to web sites.
Ferroelectric materials also have a molecular-scale dipole moment, but one characterized by a positive or negative electric charge rather than magnetic polarity. This polarization can also be manipulated; applying an external electric field toggles between that material’s two electric states, which translates into code. This critical, tunable characteristic comes from an internal subatomic asymmetry and ordering phenomena, which was imaged in detail for the first time by the transmission electron microscopes used in this study.
“Ferroelectric materials can retain information on a much smaller scale and with higher density than ferromagnetics,” Zhu said. “We’re looking at moving from micrometers (millionths of a meter) down to nanometers (billionths of a meter).”
[Morgan McCorkle, 865.574.7308,