Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


New theory for latest high-temperature superconductors

Rice, Rutgers physicists explain, predict properties of iron compounds

Physicists from Rice and Rutgers universities have published a new theory that explains some of the complex electronic and magnetic properties of iron "pnictides." In a series of startling discoveries this spring, pnictides were shown to superconduct at relatively high temperatures.

The surprising discoveries created a great deal of excitement in the condensed matter physics community, which has been scrambling to better understand and document the unexpected results.

High-temperature superconductivity -- a phenomenon first documented in 1986 -- remains one of the great, unexplained mysteries of condensed matter physics. Until the discovery of the iron pnictides (pronounced NIK-tides), the phenomena was limited to a class of copper-based compounds called "cuprates" (pronounced COO-prayts).

The new pnictide theory appears in this week's issue of Physical Review Letters.

"There is a great deal of excitement in the quantum condensed matter community about the iron pnictides," said paper co-author Qimiao Si, Rice University theoretical physicist. "For more than 20 years, our perspective was limited to cuprates, and it is hoped that this new class of materials will help us understand the mechanism for high-temperature superconductivity."

From its initial discovery, high-temperature superconductivity came as a shock to physicists. Superconductors are materials that conduct electricity without any resistance, and in 1986, the prevailing theory of superconductivity held that the phenomenon could not occur at temperatures greater than about 30 kelvins (minus 405 degrees Fahrenheit). Some cuprates have since been discovered to superconduct at temperatures higher than 140 kelvins.

The 2006 discovery of superconductivity in one iron pnictide did not receive much notice from the physics community, since it occurred only below several kelvins. In February 2008, a group from Japan discovered superconductivity above 20 kelvins in another of the iron pnictides. In March and April, several research groups from China showed that related iron pnictides superconduct at temperatures greater than 50 kelvins.

In their new theory, Si and Rutgers University theorist Elihu Abrahams explain some of the similarities and differences between cuprates and pnictides. The arrangement of atoms in both types of materials creates a "strongly correlated electron system" in which electrons interact in a coordinated way and behave collectively.

Si and Abrahams propose that the pnictides exhibit a property called "magnetic frustration," a particular atomic arrangement that suppresses the natural tendency of iron atoms to magnetically order themselves in relation to each other. These frustration effects enhance magnetic quantum fluctuations, which may be responsible for the high-temperature superconductivity.

"Precisely how this happens is one of the challenging questions in strongly correlated electron systems," Abrahams said. "But even though we don't know the precise mechanism, we are still able to make some general predictions about the behavior of pnictides, and we've suggested a number of experiments that can test these predictions." The tests include some specific forms of the electronic spectrum and spin states.

Jade Boyd | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1
21.03.2018 | Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik FHR

nachricht Taming chaos: Calculating probability in complex systems
21.03.2018 | 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: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>