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 Mars 2020 mission to use smart methods to seek signs of past life
17.08.2017 | Goldschmidt Conference

nachricht Gold shines through properties of nano biosensors
17.08.2017 | American Institute of Physics

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>