(Press-News.org) OAK RIDGE, Tenn., April 25, 2011 - Novel properties of ferroelectric materials discovered at the Department of Energy's Oak Ridge National Laboratory are moving scientists one step closer to realizing a new paradigm of electronic memory storage.
A new study led by ORNL's Peter Maksymovych and published in the American Chemical Society's Nano Letters revealed that contrary to previous assumptions, domain walls in ferroelectric materials act as dynamic conductors instead of static ones.
Domain walls, the separation zones only a few atoms wide between opposing states of polarization in ferroelectric materials, are known to be conducting, but the origin of the conductivity has remained unclear.
"Our measurements identified that subtle and microscopically reversible distortions or kinks in the domain wall are at the heart of the dynamic conductivity," Maksymovych said. "The domain wall in its equilibrium state is not a true conductor like a rigid piece of copper wire. When you start to distort it by applying an electric field, it becomes a much better conductor."
Ferroelectrics, a unique class of materials that respond to the application of an electric field by microscopically switching their polarization, are already used in applications including sonar, medical imaging, fuel injectors and many types of sensors.
Now, researchers want to push the boundaries of ferroelectrics by making use of the materials' properties in areas such as memory storage and nanoelectronics. Gaining a detailed understanding of electrical conductance in domain walls is seen as a crucial step toward these next generation applications.
"This study shows for the first time that the dynamics of these defects - the domain walls - are a much richer source of memory functionality," Maksymovych said. "It turns out you can dial in the level of the conductivity in the domain wall, making it a tunable, metastable, dynamic memory element."
The domain wall's tunable nature refers to its delayed response to changes in conductivity, where shutting off an electric field does not produce an immediate drop in conductance. Instead, the domain wall "remembers" the last level of conductance for a given period of time and then relaxes to its original state, a phenomenon known as memristance. This type of behavior is unlike traditional electronics, which rely on silicon transistors that act as on-off switches when electric fields are applied.
"Finding functionality intrinsic to nanoscale systems that can be controlled in a novel way is not a path to compete with silicon, but it suggests a viable alternative to silicon for a new paradigm in electronics," Maksymovych said.
The ORNL-led team focused on bismuth ferrite samples, but researchers expect that the observed properties of domain walls will hold true for similar materials.
"The resulting memristive-like behavior is likely to be general to ferroelectric domain walls in semiconducting ferroelectric and multiferroic materials," said ORNL co-author Sergei Kalinin.
The samples used in the study were provided by the University of California at Berkeley. Other authors are ORNL's Arthur Baddorf, Jan Seidel and Ramamoorthy Ramesh of Lawrence Berkeley National Laboratory and UC Berkeley, and Pennsylvania State University's Pingping Wu and Long-Qing Chen.
###
Part of this work was supported by the Center for Nanophase Materials Sciences at ORNL. CNMS is one of the five DOE Nanoscale Science Research Centers supported by the DOE Office of Science, premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the
largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers/.
Work at Lawrence Berkeley National Laboratory and the University of California, Berkeley, was supported by DOE's Office of Science and the Semiconductor Research Corporation.
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science.
NOTE TO EDITORS: You may read other press releases from Oak Ridge National Laboratory or learn more about the lab at http://www.ornl.gov/news. Additional information about ORNL is available at the sites below:
Twitter - http://twitter.com/oakridgelabnews
RSS Feeds - http://www.ornl.gov/ornlhome/rss_feeds.shtml
Flickr - http://www.flickr.com/photos/oakridgelab
YouTube - http://www.youtube.com/user/OakRidgeNationalLab
LinkedIn - http://www.linkedin.com/companies/oak-ridge-national-laboratory
Facebook - http://www.facebook.com/Oak.Ridge.National.Laboratory
END
CORVALLIS, Ore. – Amphibian declines around the world have forced many species to the brink of extinction, are much more complex than realized and have multiple causes that are still not fully understood, researchers conclude in a new report.
The search for a single causative factor is often missing the larger picture, they said, and approaches to address the crisis may fail if they don't consider the totality of causes – or could even make things worse.
No one issue can explain all of the population declines that are occurring at an unprecedented rate, and much faster ...
COLUMBUS, Ohio – Mosquitoes make proteins to help them handle the stressful spike in body temperature that's prompted by their hot blood meals, a new study has found.
The mosquito's eating pattern is inherently risky: Taking a blood meal involves finding warm-blooded hosts, avoiding detection, penetrating tough skin and evading any host immune response, not to mention the slap of a human hand.
Until now, the stress of the hot blood meal itself has been overlooked, researchers say.
Scientists have determined in female mosquitoes that the insects protect themselves ...
AMES, Iowa - Like people, plants experience stress. And also, like people, the response to that stress can determine success.
People can exercise, or rest, or talk about the problem.
For plants, ways to deal with stress are internal. And ISU researchers are trying to understand how they do it.
Stephen Howell is a professor of genetics, development and cell biology and former director of the Plant Sciences Institute at ISU. His research is featured in the current issue of the journal Proceedings of the National Academy of Sciences.
"We've discovered a new arm of ...
AUSTIN, Texas-A new low cost test for acute pancreatitis that gets results much faster than existing tests has been developed by scientists at The University of Texas at Austin.
The sensor, which could be produced for as little as a dollar, is built with a 12-cent LED light, aluminum foil, gelatin, milk protein and a few other cheap, easily obtainable materials.
The sensor could help prevent damage from acute pancreatitis, which is a sudden inflammation of the pancreas that can lead to severe stomach pain, nausea, fever, shock and in some cases, death.
"We've turned ...
Following a government backed business start-up scheme, search figures obtained by Google and Experian indicate a significant increase in people searching online for advice on business start-up. Bird and Co Creative, a graphic and web design company, has also experienced a rise in online leads relating to new business marketing. Traditionally, the close of the financial year brings a dip in online searches for terms relating to business start-up. However, this year the trend has changed dramatically - searches for 'business plan UK' were up 60pc and 'small business loan' ...
The formation of the new coalition government has brought with it numerous changes. The Equality Act 2010 is now under review with considerations to scrap it altogether. Following years of campaigning the act was finally put in place to unify the existing equality laws. The Institute of Equality and Diversity Practitioners (IEDP) are challenging the government's proposed changes and have called a number of emergency meetings to discuss their challenge. Scrapping the act will weaken their powers and void the hard work which has been put into promoting equality and diversity ...
VIDEO:
University of Missouri veterinarians have changed the way veterinarians treat diabetes in animals by adapting a device used to monitor glucose in humans.
Click here for more information.
COLUMBIA, Mo. – Studies show the incidence of diabetes in dogs has increased 200 percent over the past 30 years. Now, University of Missouri veterinarians have changed the way veterinarians treat diabetes in animals by adapting a device used to monitor glucose in humans.
Dogs are ...
Regular preventative maintenance is necessary to keep a restaurant running efficiently and performing to its maximum capability. However, some restaurants may also experience unnecessary visits, which are visits that could be avoided by controlling one of the most common commodity items: water.
Water not only affects a restaurant's utility bills, but it can also be the source of unnecessary maintenance. How often is a service company performing ice machine cleanings? Or descaling a piece of espresso or steam equipment? Controlling water quality can help to optimize ...
Monday, April 25, 2011
CHAPEL HILL, N.C. – Unintentional overdose deaths in teens and adults have reached epidemic proportions in the U.S. In some 20 states in 2007 the number of unintentional drug poisoning deaths exceeded either motor vehicle crashes or suicides, two of the leading causes of injury death. Prescription opioid pain medications are driving this overdose epidemic. Opioid pain medications were also involved in about 36 percent of all poisoning suicides in the U.S. in 2007.
In a commentary article released ahead of the print version in the April 19, 2011 ...
WEST LAFAYETTE, Ind. - Spicing up your daily diet with some red pepper can curb appetite, especially for those who don't normally eat the popular spice, according to research from Purdue University.
"We found that consuming red pepper can help manage appetite and burn more calories after a meal, especially for individuals who do not consume the spice regularly," said Richard Mattes, distinguished professor of foods and nutrition who collaborated with doctoral student Mary-Jon Ludy. "This finding should be considered a piece of the puzzle because the idea that one small ...
