Contact Information:

Media Contact

Tona Kunz

Twitter: argonne

Kredyty mieszkaniowe Kredyty mieszkaniowe

Sprawdź aktualny ranking najlepszych kredytów mieszkaniowych w Polsce - atrakcyjne kredytowanie nieruchomości. - Press Release Distribution
RSS - Press News Release
Add Press Release

Insights into obscure transition uncovered by X-rays

( The list of potential mechanisms that underlie an unusual metal-insulator transition has been narrowed by a team of scientists using a combination of X-ray techniques. This transition has ramifications for material design for electronics and sensors.

The transition between being electrically conductive (metallic) at high temperatures and electrically insulating at lower temperatures is known as a metal-insulator transition (MIT). Pinpointing the activation mechanism that allows crystals used in devices such as transistors in electronics and temperature-based sensor control systems used in manufacturing to change electrical state is key to developing new devices that are smaller and more efficient than those in use today.

For example, transistors, and most electronics, function by tuning conductivity, which is essentially using the level of electrical resistance as an on-off switch. Designing new electronic devices has been largely driven by trial and error. Understanding what causes large changes in electrical conductivity, as in an MIT, can allow us to design new materials that are cheaper or have higher-performance properties.

"If we understand how the transition occurs, we can exploit that knowledge to design new materials to customize transistor properties, such as selecting levels of conductivity to make transistors more efficient or to make sensors operate in customized ranges," said Mary Upton, a scientist at the Advanced Photon Source (APS), a U.S. Department of Energy User Facility at Argonne National Laboratory.

The team of researchers from Argonne and Lawrence Berkeley national laboratories and the University of Arkansas made inroads in understanding this transition by using the APS to study rare-earth crystal family perovskites, including the rare-earth atom compounds nickelates. Nickelates are compounds that contain a central nickel atom bonded to oxygen or oxygen-containing groups and are considered an ideal model for the study of this transition.

The team studied thin films of neodymium nickel oxide (NdNiO3), a nickelate, using three different beamlines at APS, which allowed an in-depth exploration of the samples. Nickelates are considered an ideal model for studying the transition because they display strongly correlated electronic behavior that gives rise to unique electronic and magnetic properties.

Many different theories exist to explain the mechanics that drive metal-insular transition. The team was able to rule out those theories based on the charge order of the particles in the material, including the widely held theory that an electronic checkerboard pattern, which has been observed in bulk, triggers the transition. This checkerboard pattern is also called charge order and charge disproportionation and is observed or not observed by using the X-ray analysis technique of resonant diffraction. The results were published in July in the journal Physical Review Letters in a paper titled "Novel electronic behavior facilitating the NdNiO3 metal-insulator transition".

"APS beamlines provide the high photon flux and energy that are critical when dealing with subtle electronic effects," said Upton, lead author on the paper. "State-of-the-art optics and collaboration between beamlines allows unparalleled detail in the study of materials. Measurements from Resonant X-ray Diffraction, X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering (RIXS) combined to draw a new picture of the material. The application of the RIXS technique to a long-standing problem was made possible by improved capabilities in thin film measurements at the beamline."

To study the transition, chemically identical film samples were grown with small structural distortions induced by epitaxial strain induced when growing a single crystal film on top of a crystalline substrate. Slight difference in lattice constants brought about substantial changes in electronic behavior. The effect of strain has been known for years, but never explained. A film with a tensile distortion, where all the atoms are more distant from each other, exhibits a state transition. A film grown with a slightly compressive distortion, where all atoms are closer together than in bulk, is electrically conductive at all temperatures. Neither film, however, exhibited an electronic checkerboard so it cannot be a pre-requisite for a MIT.

The measurements also suggest that tensile strain facilitates the transfer of electrons between two elementally different atoms. This observation was a surprise because the atoms in question had been assumed to be isolated from each other. These results strongly suggest a need to re-examine other, similar state transitions in perovskites.

"The state transition is neither what is called a pure Mott-Hubbard transition, despite electron localization, nor a simple charge-transfer transition," said Philip Ryan, a scientist working at the APS and co-author on the paper.

This new insight into the state transition in nickelates will help guide the design of new electronic devices.


This research was supported by grants from the U.S. Department of Energy and Department of Defense, and the University of Illinois at Chicago and Argonne. The use of the APS was supported by the DOE. The work was done at the following APS beamlines: 4-ID-D, 6-ID-B, and the Sector 27 RIXS beamline, which recently incorporated 9-ID-B.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy'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

The unit cell of the nickelate NdNiO3 is shown with Nd represented by blue, O by red and Ni by green. The Ni electron density (green) is believed to transfer to the Nd (blue) during the metal-insulator transition. (Image courtesy Mary Upton; click to view larger.) The unit cell of the nickelate NdNiO3 is shown with Nd represented by blue, O by red and Ni by green. The Ni electron density (green) is believed to transfer to the Nd (blue) during the metal-insulator transition. (Image courtesy Mary Upton; click to view larger.)


Disney Research demonstrates LEDs that use visible light to talk to each other and internet

The light that typically floods homes, offices and public buildings could provide something more than illumination. Scientists at Disney Research and ETH Zurich have demonstrated that light could be a medium for light bulbs to communicate - with each other, with objects and with the Internet. Transmitting signals via light is nothing new; Alexander Graham Bell showed that speech could be conveyed with light in the 1880s, years before speech was first transmitted via radio. The Disney researchers, however, have created networking technology that makes it possible for LED ...

Innovative imaging technique reveals new cellular secrets

Innovative imaging technique reveals new cellular secrets
KANSAS CITY, MO -- Cellular mitosis depends in part on small organelles that extend spindles to pull apart chromosome pairs. Before they can perform this and other essential tasks, these tiny cylindrical structures -- known as centrioles in animals and spindle pole bodies (SPBs) in yeast -- must themselves duplicate. However, much about this nanoscale process has remained veiled by the limits of current microscopy. Optical approaches cannot resolve objects below certain wavelength limits, while non-optical approaches like electron microscopy (EM) can only study nonliving ...

Predicting tornadoes months or even seasons in advance

Predicting tornadoes months or even seasons in advance
What if tornado activity could be forecasted months, even seasons in advance? Thanks to a new model developed at the University of Toronto Scarborough, that ability could soon become a reality. "The aim is to predict ahead to the following year or subsequent years about whether we'll get above or below average tornado activity in a given area," says Vincent Cheng, a postdoctoral fellow in UTSC's Ecological Modelling Lab. The model, developed by Cheng, Professor George Arhonditsis and Professor Bill Gough in UTSC's Climate Lab along with colleagues at Environment Canada, ...

Ebola virus mutations may help it evade drug treatment

Genetic mutations called "escape variants" in the deadly Ebola virus appear to block the ability of antibody-based treatments to ward off infection, according to a team of U.S. Army scientists and collaborators. Their findings, published online this week in the journal Cell Reports, have implications for the continued development of therapeutics to treat Ebola virus disease, which has claimed the lives of over 11,000 people in West Africa since last year. Ebola virus overruns the immune system, thus overwhelming the host's ability to fight off the infection. One strategy ...

Stellar discovery by Queen's researcher

PhD candidate Matt Shultz has discovered the first massive binary star, epsilon Lupi, in which both stars have magnetic fields. A binary star is a star system consisting of two or more stars, orbiting around their common centre of mass. For the past few years, the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) collaboration, formed to study the magnetic properties of close binaries, has been trying to find such an object. They have now discovered one using the Canada-France-Hawaii Telescope. "The origin of magnetism amongst massive stars is ...

UK researchers find 'dormant' parasite cysts are actually quite active

LEXINGTON, Ky. (Sept. 8, 2015) -- A new University of Kentucky study in the journal mBio shows that tissue cysts of the parasite Toxoplasma gondii, long thought to be dormant, are quite active. Led by Anthony Sinai, professor at the UK College of Medicine, the study has significant implications on the understanding of chronic toxoplasmosis in the brain, a condition suggested to contribute to a range of neurological diseases including schizophrenia in humans, and the modulation of behavior in rodents. Toxoplasmosis can be acquired from the droppings of infected cats ...

Extreme pressure causes osmium to change state of matter

Using metallic osmium (Os) in experimentation, an international group of researchers have demonstrated that ultra-high pressures cause core electrons to interplay, which results in experimentally observed anomalies in the compression behavior of the material. Os is one of Earth's most exceptional elemental materials, possessing the highest known density at ambient pressure, one of the highest cohesive energies and melting temperatures, and an incompressibility that is almost comparable to that of diamond. Researchers believe that the ability to affect core electrons ...

Making a difference with open source science equipment

Making a difference with open source science equipment
Open source lab equipment is the focus of a new study, published in Science and Public Policy. Joshua Pearce, an associate professor of materials science and engineering as well as electrical and computer engineering at Michigan Tech, led the research. Pearce proposes that instead of spending millions of dollars every year replacing quickly obsolescent equipment, that money could be redirected to developing open source tools that are "upgradeable and transformable--they will be continuously updated" using digital manufacturing techniques such as 3-D printing. The benefits ...

Inside climate politics

The politics of climate change are often depicted as a simple battle, between environmentalists and particular industries, over government policy. That's not wrong, but it's only a rough sketch of the matter. Now a paper co-authored by MIT economist Christopher Knittel fills in some important details of the picture, revealing an essential mechanism that underlies the politics of the climate battle. Specifically, as Knittel and his colleagues demonstrate, at least one climate policy enacted by Congress -- on transportation fuels -- contains a crucial asymmetry: It imposes ...

Study reveals connection between fitness level, brain activity, and executive function

The aging process is associated with declines in brain function, including memory and how fast our brain processes information, yet previous research has found that higher levels of cardiorespiratory fitness in older adults leads to better executive function in the brain, which helps with reasoning and problem solving. Higher cardiorespiratory fitness levels have also been found to increase brain volume in key brain regions. A new study from a team at the Beckman Institute for Advanced Science and Technology at the University of Illinois reveals the connection between ...


How your brain decides blame and punishment -- and how it can be changed

Uniquely human brain region enables punishment decisions

Pinpointing punishment

Chapman University publishes research on attractiveness and mating

E-cigarettes: Special issue from Nicotine & Tobacco Research

Placental problems in early pregnancy associated with 5-fold increased risk of OB & fetal disorders

UT study: Invasive brood parasites a threat to native bird species

Criminals acquire guns through social connections

Restoring ocean health

Report: Cancer remains leading cause of death in US Hispanics

Twin study suggests genetic factors contribute to insomnia in adults

To be fragrant or not: Why do some male hairstreak butterflies lack scent organs?

International team discovers natural defense against HIV

Bolivian biodiversity observatory takes its first steps

Choice of college major influences lifetime earnings more than simply getting a degree

Dominant strain of drug-resistant MRSA decreases in hospitals, but persists in community

Synthetic biology needs robust safety mechanisms before real world application

US defense agencies increase investment in federal synthetic biology research

Robots help to map England's only deep-water Marine Conservation Zone

Mayo researchers identify protein -- may predict who will respond to PD-1 immunotherapy for melanoma

How much water do US fracking operations really use?

New approach to mammograms could improve reliability

The influence of citizen science grows despite some resistance

Unlocking secrets of how fossils form

What happens on the molecular level when smog gets into the lungs?

Using ultrasound to clean medical instruments

Platinum and iron oxide working together get the job done

Tiny silica particles could be used to repair damaged teeth, research shows

A quantum lab for everyone

No way? Charity's logo may influence perception of food in package

[] Insights into obscure transition uncovered by X-rays is a service of DragonFly Company. All Rights Reserved.
Issuers of news releases are solely responsible for the accuracy of their content.