Featured Research

from universities, journals, and other organizations

Data storage of tomorrow: Ferroelectricity on the nanoscale

Date:
July 10, 2012
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
Scientists have brought some clarity to the here-to-fore confusing physics of ferroelectric nanomaterials, pointing the way to multi-terabyte-per-square-inch of non-volatile computer memory chips.

Atomic-resolution images of germanium telluride nanoparticles from Berkeley Lab’s TEAM I electron microscope, and electron holographic images of barium titanate nanoparticles (below) from BNL yielded the first detailed experimental information on ferroelectric order at the nanoscale.
Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory

Promising news for those who relish the prospects of a one-inch chip storing multiple terabytes of data, some clarity has been brought to the here-to-fore confusing physics of ferroelectric nanomaterials. A multi-institutional team of researchers, led by scientists at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) has provided the first atomic-scale insights into the ferroelectric properties of nanocrystals. This information will be critical for development of the next generation of nonvolatile data storage devices.

Working with the world's most powerful transmission electron microscope, the researchers mapped the ferroelectric structural distortions in nanocrystals of germanium telluride, a semiconductor, and barium titanate, an insulator. This data was then combined with data from electron holographic polarization imaging to yield detailed information on the polarization structures and scaling limits of ferroelectric order on the nanoscale.

"As we scale down our device technology from the microscale to the nanoscale, we need a better understanding of how critical material properties, such as ferroelectric behavior, are impacted," says Paul Alivisatos, director of Berkeley Lab and one of the principal investigators in this research. "Our results provide a pathway to unraveling the fundamental physics of nanoscale ferroelectricity at the smallest possible size scales."

Alivisatos, who is also the Larry and Diane Bock Professor of Nanotechnology at the University of California (UC) Berkeley, is a corresponding author of a paper describing this work in the journal Nature Materials titled "Ferroelectric order in individual nanometrescale Crystals." The other corresponding author is Ramamoorthy Ramesh, a senior scientist with Berkeley Lab's Materials Sciences Division and the Plato Malozemoff Professor of Materials Science and Physics for UC Berkeley.

Ferroelectricity is the property by which materials can be electrically polarized, meaning they will be oriented in favor of either a positive or negative electrical charge. This polarization can be flipped with the application of an external electrical field, a property that could be exploited for nonvolatile data storage, similar to the use of ferromagnetic materials today but using much smaller, far more densely packed devices.

"Although much progress has been made towards understanding nanoscale photophysical magnetic and other functional properties, understanding the basic physics of ferroelectric nanomaterials remains far less advanced," says co-principal investigator Ramesh, who attributes contradicting reports on nanoscale ferroelectricity in part to the lack of high-quality, nanocrystals of ferroelectric materials that feature well-defined sizes, shapes and surfaces.

"Another problem has been the reliance on ensemble measurements rather than single particle techniques," he says. "Statistical-average measurement techniques tend to obscure the physical mechanisms responsible for profound changes in ferroelectric behavior within individual nanocrystals."

The Berkeley Lab-led research team was able to map ferroelectric structural distortions within individual nanocrystals thanks to the unprecedented capabilities of TEAM I, which is housed at Berkeley Lab's National Center for Electron Microscopy (NCEM). TEAM stands for "Transmission Electron Aberration-corrected Microscope." TEAM I can resolve images of structures with dimensions as small as one half‑angstrom -- less than the diameter of a single hydrogen atom.

The maps produced at TEAM I of ferroelectric distortion patterns within the highly conducting germanium telluride nanocrystals were then compared with electron holography studies of insulating nanocubes of barium titanate, which were carried out by collaborators at Brookhaven National Laboratory (BNL).

"Electron holography is an interferometry technique using coherent electron waves," said BNL physicist and co-author of the Nature Materials paper Myung-Geun Han. "Firing focused electron waves through the ferroelectric sample creates what's called a phase-shift, or an interference pattern that reveals details of the targeted structure. This produces an electron hologram, which we can use to directly see local electric fields of individual ferroelectric nanoparticles."

These combined studies enabled the independent examination of depolarizing field and surface structure influences and thereby enabled the research team to identify the fundamental factors governing the nature of the ferroelectric polarized state at finite dimensions. The results indicate that a monodomain ferroelectric state with linearly ordered polarization remains stable in these nanocrystals down to dimensions of less than 10 nanometers. Also, room-temperature polarization flipping was demonstrated down to dimensions of about five nanometers. Below this threshold, ferroelectric behavior disappeared. This indicates that five nanometers is likely a size limit for data storage applications, the authors state.

"We also showed that ferroelectric coherence is facilitated in part by control of particle morphology, which along with electrostatic boundary conditions is found to determine the spatial extent of cooperative ferroelectric distortions," Ramesh says. "Taken together, our results provide a glimpse of the structural and electrical manifestations of ferroelectricity down to its ultimate limits."

Also co-authoring the Nature Materials paper in addition to Alivisatos, Ramesh and Han were Mark Polking, Amin Yourdkhani, Valeri Petkov, Christian Kisielowski, Vyacheslav Volkov, Yimei Zhu and Gabriel Caruntu.

This research was supported by the DOE Office of Science.


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mark J. Polking, Myung-Geun Han, Amin Yourdkhani, Valeri Petkov, Christian F. Kisielowski, Vyacheslav V. Volkov, Yimei Zhu, Gabriel Caruntu, A. Paul Alivisatos, Ramamoorthy Ramesh. Ferroelectric order in individual nanometre-scale crystals. Nature Materials, 2012; DOI: 10.1038/nmat3371

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Data storage of tomorrow: Ferroelectricity on the nanoscale." ScienceDaily. ScienceDaily, 10 July 2012. <www.sciencedaily.com/releases/2012/07/120710172154.htm>.
DOE/Lawrence Berkeley National Laboratory. (2012, July 10). Data storage of tomorrow: Ferroelectricity on the nanoscale. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2012/07/120710172154.htm
DOE/Lawrence Berkeley National Laboratory. "Data storage of tomorrow: Ferroelectricity on the nanoscale." ScienceDaily. www.sciencedaily.com/releases/2012/07/120710172154.htm (accessed July 23, 2014).

Share This




More Matter & Energy News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins