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 A tale of two pulsars' tails: Plumes offer geometry lessons to astronomers
18.01.2017 | Penn State

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>