Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Superconductivity - Electrons in Single File Provide New Insights

22.11.2004


A team at the University of Innsbruck, Austria has been successful in conducting electrons in metals along predetermined channels. This behaviour, observed for the first time in metals, provides important insights into the interactions of electrons - and on how the phenomenon of the current flow without any resistance loss, termed super-conductivity, can occur. Thereby this project aided by the Austrian Science Fund (FWF) combines fundamental research, at its best, with potential applications in the future.



High-temperature superconductors are ceramic materials that conduct electricity without resistance, and thus without loss, below a certain temperature. At higher temperatures, the behaviour rapidly changes and experiences resistance. Such discontinuous changes due to external influences are typical for the so-called "smart materials". Their discontinuous behaviour is closely linked with a mutual dependence of spatially confined electrons, giving rise to a commonly coordinated motion pattern. So far this dependence termed as correlation had been observed only in non-metals.

Electrons in Single File...


Now a team under Prof. Erminald Bertel, Institute of Physical Chemistry, University of Innsbruck, Austria, has for the first time succeeded in forcing the electrons in a metal as well into such a mutual dependence. For this purpose, the researchers first of all created nano-structures on the surface of metal single crystals, which are crystals with uniform lattice structure.

Prof. Bertel, the project director, explains: "Normally, the electrons in a metal spread in all three directions in space. But in metal single crystals, some of the electrons are confined to the surface and therefore can move only in two dimensions. Nano-structures can then further restrict their freedom of movement. To produce such structures, the surfaces of copper crystals for instance can be oxidised in such a way that free copper channels of 3 nanometres width lie between ridges of copper oxide. In these channels, the electrons can only move unidimensionally. Also on platinum crystals atom chains can be arranged to run parallel across the surface with approximately 0.8 nanometre spacing. Certain electrons can then only spread along these chains."

Once the electrons were forced into a controlled motion along the channels or chains, Professor Bertel’s team was able to observe something fascinating - depending on experimental conditions, the electrons move within the individual channels entirely independent of each other, i.e. incoherently, or they align their movements across all channels. In such a state of motion that is described as coherent, the electrons can no longer be assigned to individual channels, but are "de-localised".

... When the Temperature is Right

For a closer analysis of the states of the electrons, the researchers at Innsbruck also made use of photoelectron spectroscopy. In this method, the energetic distribution of electrons emitted from the surface due to light (photon) absorption is measured. Interestingly, the spectra showed that above a critical temperature, the electrons pass from a coherent into an incoherent state.

A completely similar temperature dependence of photoelectron spectra, however, is already known in superconductors, but was explained differently so far. Thus the observations of the Innsbruck team suggest that the superconductivity in ceramic superconductors is connected to a transition of electrons from an incoherent state into a coherent state.

Prof. Bertel: "The transport of electricity without loss due to electric resistance could mean a significant contribution to energy saving and to the solution of some environmental problems. But at present our comprehension of superconductivity does not allow the synthesis of superconductive materials that can afford a commercial use under economical conditions. Our team has achieved in adding a small chip to the mosaic, which brings us a little closer to such applications."

Prof. Erminald Bertel | alfa
Further information:
http://www.fwf.ac.at/en/press/superconductivity.html
http://www.prd.at
http://www.uibk.ac.at

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>