Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists offer new theory for iron compounds

16.03.2009
Theory makes predictions about latest high-temp superconductor

An international team of physicists from the United States and China this week offered a new theory to both explain and predict the complex quantum behavior of a new class of high-temperature superconductors.

The findings, which are available online this week from the Proceedings of the National Academy of Sciences, are about materials known as iron pnictides (pronounced NIK-tides). The discovery of high-temperature superconductivity in pnictides a year ago is a boon for physicists who have struggled for more than two decades to explain the phenomena based on observations from a class of copper-based superconductors called cuprates (pronounced COO-prayts).

"Our research addresses the quantum magnetic fluctuations that have been observed in iron pnictides and offers a theory to explain how electron-electron interactions govern this behavior," said study co-author Qimiao Si, a physicist from Rice University. "The origins of superconductivity are believed to be rooted in these effects, so understanding them is extremely important."

In the PNAS paper, Si and collaborators from Rutgers University, Zhejiang University and the Los Alamos National Laboratory explain some of the similarities and differences between cuprates and pnictides. Under certain circumstances, the atomic arrangements in both materials cause electrons to behave collectively, marching in lock step with one another. Experimental physicists study how changes in temperature, magnetic fields and the like cause the coordinated effects to change. They also look for changes arising from differences in the way the compounds are prepared, such as when other substances are added via a technique called "doping."

"In cuprates, the parent compounds are not metallic, and they only become superconducting when they are doped," said Rutgers University physicist and co-author Elihu Abrahams. "In contrast, the parent compounds of pnictides are metallic, but like the undoped cuprates they exhibit a quantum magnetic property called antiferromagnetism."

Based on what's known about electron-electron interactions and about antiferromagnetism in other metals, the authors created a theoretical framework to explain the behavior of the pnictides, offering some specific predictions about how they will behave as they change phases.

Matter is commonly transformed when it changes phases; the melting of ice, for example, marks water's change from a solid phase to a liquid phase. In materials like cuprates and pnictides, the tendency of electrons to act in concert can lead to "quantum" phase changes, shifts from one phase to another that arise entirely from the movements of subatomic particles. The study of quantum "critical points," the tipping points that mark these phase changes, is known as "quantum criticality."

"Our work opens up the iron pnictides as a new setting to study the rich complexities of quantum criticality," said Si. "This is much needed since quantum critical points, which are believed to be important for a wide range of quantum materials, have so far been observed in only a small number of materials."

Jade Boyd | EurekAlert!
Further information:
http://www.rice.edu

More articles from Physics and Astronomy:

nachricht Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich

nachricht Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>