Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unprecedented subatomic details of exotic ferroelectric nanomaterials

09.07.2012
Successful imaging of individual atoms and associated electric fields in ferroelectrics could lead the way to a new era of advanced electronics

As scientists learn to manipulate little-understood nanoscale materials, they are laying the foundation for a future of more compact, efficient, and innovative devices.

In research to be published online July 8 in the journal Nature Materials, scientists at the U.S. Department of Energy's Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, and other collaborating institutions describe one such advance - a technique revealing unprecedented details about the atomic structure and behavior of exotic ferroelectric materials, which are uniquely equipped to store digital information. This research could guide the scaling up of these exciting materials and usher in a new generation of advanced electronics.

Brookhaven scientists used a technique called electron holography to capture images of the electric fields created by the materials' atomic displacement with picometer precision - that's the trillionths-of-a-meter scale crucial to understanding these promising nanoparticles. 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, with major implications for data storage.

"This kind of detail is just amazing - for the first time ever we can actually see the positions of atoms and link them to local ferroelectricity in nanoparticles," said Brookhaven physicist Yimei Zhu. "This kind of fundamental insight is not only a technical milestone, but it also opens up new engineering possibilities."

Ferroelectrics are perhaps best understood as the mysterious cousins of more familiar ferromagnetic materials, commonly seen in everything from refrigerator magnets to computer hard drives. As the name suggests, ferromagnetics have intrinsic magnetic dipole moments, meaning that they are always oriented toward either "north" or "south." These dipole moments tend to align themselves on larger scales, giving rise to the magnetization responsible for attraction and repulsion. Applying an external magnetic field can actually flip that magnetization, allowing programmers and engineers to manipulate the material.

Similarly, 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, but flipping the charge requires an external electric field. 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 new study.

Current magnetic memory devices, such as the hard drives in most computers, "write" information into ferromagnetic materials by flipping that intrinsic 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. The remarkable ability of these materials to retain information even when turned off - what's called nonvolatile storage - makes them an essential building block for our increasingly digital world.

In the emerging ferroelectric model of data storage, applying an electric field toggles between that material's two electric states, which translates into code. When scaled up similarly to ferromagnetics, that process can manifest on a computer as the writing or reading of digital information. And ferroelectric materials may trump their magnetic counterparts in ultimate efficacy.

"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). And that's what's really exciting, because we now know that on the nanoscale each particle can become its own bit of information. We knew very little about manipulating ferroelectric behavior in nanomaterials before this."

The trick to scaling up individual ferroelectric nanoparticles into useful devices is understanding just how tightly together they can be packed and ordered without compromising their distinct polarizations, which theory suggests should be extremely difficult to achieve. The electron holography experiments conducted at Brookhaven Lab demonstrated a method for determining those parameters under a range of conditions.

"Electron holography is an interferometry technique using coherent electron waves," said Brookhaven physicist Myung-Geun Han. "When electron waves pass through a ferroelectric sample, they are influenced by local electric fields, yielding a so-called phase-shift. The interference pattern between the electrons that pass through electric fields and those that don't creates what's called an electron hologram, which allows us to directly 'see' those local electric fields around individual ferroelectric nanoparticles."

Local electric fields emanate from ferroelectric nanoparticles, and these "fringing" fields are like the functional footprint of a particle's polarity. Consider the way a small magnet's effects can be felt even at a slight distance from its surface - a similar field exists in ferroelectric materials. When imaged by electron holography, the fringing field indicates the integrity of electrical polarity and the distance required between particles before they begin to interfere with each other.

The study revealed that the electric polarity could remain stable for individual ferroelectric materials, meaning that each nanoparticle can be used as a data bit. But because of their fringing fields, ferroelectrics need a little elbow room (on the order of five nanometers) to effectively operate. Otherwise, once scaled up for computer storage, they can't keep code intact and the information becomes garbled and corrupted. Understanding the atomic-scale properties revealed in this study will help guide implementation of these exotic particles.

"Properly used, ferroelectrics could ramp up memory density and store an unparalleled multiple terabytes of information on just one square inch of elec tronics," Han said. "This brings us closer to engineering such devices."

The ferroelectric nanoparticles tested, semiconducting germanium telluride and insulating barium titanate, were engineered at Lawrence Berkeley National Laboratory and brought to Brookhaven Lab for the electron holography experiments. Additional experiments using x-ray diffraction were conducted at Argonne National Laboratory's Advanced Photon Source.

The work featured collaborators from the University of California at Berkeley, the University of New Orleans, Central Michigan University, Lawrence Berkeley National Lab and Brookhaven National Lab. In addition to Zhu and Han, Brookhaven scientist Vyacheslav Volkov was also involved in the project. The research was funded by DOE's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit: http://science.energy.gov/.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization. Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more at http://www.bnl.gov/newsroom , or follow Brookhaven Lab on Twitter, http://twitter.com/BrookhavenLab .

Karen McNulty Walsh | EurekAlert!
Further information:
http://www.bnl.gov

More articles from Materials Sciences:

nachricht Research shows black plastics could create renewable energy
17.07.2019 | Swansea University

nachricht A new material for the battery of the future, made in UCLouvain
17.07.2019 | Université catholique de Louvain

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Bridging the nanoscale gap: A deep look inside atomic switches

22.07.2019 | Physics and Astronomy

Regulation of root growth from afar: How genes from leaf cells affect root growth

22.07.2019 | Life Sciences

USF geoscientists discover mechanisms controlling Greenland ice sheet collapse

22.07.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>