Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New particle explains odd behavior in cuprate superconductors

18.07.2007
New fundamental particles aren't found only at Fermilab and at other particle accelerators. They also can be found hiding in plain pieces of ceramic, scientists at the University of Illinois report.
The newly formulated particle is a boson and has a charge of 2e, but does not consist of two electrons, the scientists say. The particle arises from the strong, repulsive interactions between electrons, and provides another piece of the high-temperature superconductivity puzzle.

Twenty-one years ago, superconductivity at high temperatures was discovered in copper-oxide ceramics (cuprates). Existing explanations of superconductivity proved inadequate because, unlike low-temperature superconductors, which are metals, the parent materials from which all high-temperature superconductors arise are insulators.

Now, a new theory suggests something has been overlooked. "Hidden in the copper-oxide materials is a new particle, a boson with a charge of 2e," said Philip Phillips, a professor of physics at Illinois.

Surprisingly, this boson is not formed from the elementary excitations - that is, electrons and ions. Instead, the particle emerges as a remnant of the strong interactions between electrons in the normal state.

"High- and low-energy scales are inextricably coupled in the cuprates," Phillips said. "Normally, when you remove a single electron from most systems, one empty state is created. In the cuprates, however, when you remove an electron, you create two empty states - both of which occur at low energy, but paradoxically, one of the states comes from the high-energy scale."

Experimental evidence of this "one to two" phenomenon was first reported in 1990 and explained phenomenologically by University of Groningen physicist George A. Sawatzky (now at the University of British Columbia) and colleagues. What was missing was a low-energy theory that explained how a high-energy state could live at low energy.

Phillips, with physics professor Robert G. Leigh and graduate student Ting-Pong Choy, have constructed such a theory, and have shown that a charged 2e boson makes this all possible.

"When this 2e boson binds with a hole, the result is a new electronic state that has a charge of e," Phillips said. "In this case, the electron is a combination of this new state and the standard, low-energy state. Electrons are not as simple as we thought."

The new boson is an example of an emergent phenomenon - something that can't be seen in any of the constituents, but is present as the constituents interact with one another.

By constructing a low-energy theory of the cuprates, the researchers have moved a step closer to unraveling the mystery of high-temperature superconductivity.

"Until we understand how these materials behave in their normal state, we cannot understand the mechanism behind their high-temperature superconductivity," Phillips said.

Phillips, Leigh and Choy present their mathematical proof for the new boson in a paper accepted for publication in the journal Physical Review Letters. The National Science Foundation provided partial funding for this work.

Editor's note: To reach Philip Phillips, call 217-244-2003; e-mail:
dimer@uiuc.edu.

To view or to subscribe to the RSS feed for Science News at Illinois, please go to: http://webtools.uiuc.edu/rssManager/608/rss.xml.

James E. Kloeppel | University of Illinois
Further information:
http://www.news.uiuc.edu

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

Smart Computers

21.08.2017 | Information Technology

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>