The finding, published in Nano Letters, could change the conventional wisdom that accommodating the strain inherent during the formation of epitaxial thin films necessarily involves structural defects, said Lee, a member of the Department of Energy lab's Materials Science and Technology Division.
A schematic of a regular atomic array of ferromagnetic nano-domains formed due to an unconventional strain relaxation.
Instead, the researchers found that some materials, in this case cobaltite, form structurally well ordered atomic patterns that can change their magnetic properties and effectively minimize the size mismatch with the crystalline substrate.
Epitaxial thin films, used in nanotechnology and semiconductor fabrication, are created by growing a crystal layer of one material on another in such a way that the crystalline structures align. The challenge is to grow the film coherently with minimal defects, which can have a catastrophic effect on a material's performance.
"We discovered properties that were not readily apparent in crystal, or bulk, form, but in thin-film form we were able to clearly see the atomically ordered lattice structure of lanthanum cobaltite," Lee said. "With this knowledge, we hope to be able to tailor the physical properties of a material for many information and energy technologies."
The researchers studied the material in different strain states using scanning transmission electron microscopy complemented by X-ray and optical spectroscopy. Using these instruments, the scientists could see unconventional strain relaxation behavior that produced stripe-like lattice patterns. The result is a material with useful magnetic properties and highly suitable for sensors and ionic conductors used in, for example, batteries.
This discovery and the ability to engineer the structure of materials could lead to advanced cathode materials in solid oxide fuel cells and batteries that can be charged much faster.
"Since cobaltites are promising candidates for magnetic sensors, ionic conductors and surface catalysts, this discovery provides a new understanding that can be used for artificial tuning of magnetism and ionic activities," Lee said.
Contributing to the paper were ORNL's Woo Seok Choi and Hyoungjeen Jeen and authors from Seoul National University, the University of British Columbia, IFW Dresden's Leibniz Institute for Solid Sate and Materials Research, Max Planck-UBC Centre for Quantum Materials, Max Planck Institute for Solid State Research and the University of Saskatchewan.
The paper, titled "Strain-Induced Spin States in Atomically Ordered Cobaltites," is available at http://pubs.acs.org/doi/abs/10.1021/nl302562f. Funding for this work was provided primarily by the U.S. Department of Energy's Office of Science, Basic Energy Sciences. Optical measurements were performed in part at the Center for Nanophase Materials Sciences, a DOE-Basic Energy Sciences user facility.
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/.
UT-Battelle manages ORNL for the Office of Science. The 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/
Epoxy compound gets a graphene bump
14.11.2018 | Rice University
Automated adhesive film placement and stringer integration for aircraft manufacture
15.11.2018 | Fraunhofer IFAM
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences