Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researcher solve one mystery of high-temperature superconductors

29.11.2005


An experimental mystery -- the origin of the insulating state in a class of materials known as doped Mott insulators -- has been solved by researchers at the University of Illinois at Urbana-Champaign. The solution helps explain the bizarre behavior of doped Mott insulators, such as high-temperature copper-oxide superconductors.



In a paper published in the Nov. 2 issue of the journal Physical Review Letters, physics professor Philip Phillips and graduate student Ting-Pong Choy show that lightly doped Mott insulators are, in fact, still insulators. The scientists’ theoretical results confirm previous experimental findings obtained by other researchers.

Unlike low-temperature superconductors, which are metals, high-temperature superconductors are insulators in their normal state. This has puzzled scientists, because half of the electron states are empty.


"Mott insulators have many available states for electrons to occupy, so you would expect these materials to conduct like metals," Phillips said. "Experiments have shown, however, that they act as insulators."

Even more surprising, when Mott insulators are lightly doped with holes -- thereby creating even more places for electrons to occupy -- the material still refuses to conduct.

Strong electron interaction is the key to understanding doped Mott insulators, Phillips said. "All energy scales are inextricably coupled. If you attempt to separate them, you destroy the physics of the Mott state."

The fact that lightly doped Mott insulators are still insulators is an intrinsic property of Mott physics (that is, Mottness), the researchers claim. The insulating state is not caused by disorder, exotic excitations or something external to the system.

"In most materials, if you kill superconductivity by applying a large magnetic field, the resistivity falls to some finite value," Phillips said. "In doped Mott insulators, however, the resistivity climbs to infinity. The background state uncovered as a result of destroying superconductivity is an insulating state."

A future experiment could easily prove the researchers’ claims. While chemical doping causes disorder in the material, the technique of photodoping creates holes without causing disorder.

"If experimenters create such holes and still see this insulating state, then we will know for a fact that insulating doped Mott insulators is due to Mottness," Phillips said.

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>