Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New theory for latest high-temperature superconductors

15.08.2008
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:
http://www.rice.edu

More articles from Physics and Astronomy:

nachricht Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

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: 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...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

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

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>