Posted: November 9, 2009

Oscillating curves unhinge theories

(Nanowerk News) At the High-Magnetic Field Laboratory (HLD) at Forschungszentrum Dresden-Rossendorf (FZD) highest magnetic fields are to be used for material research. Here physicists from the Walther-Meißner-Institute of the Bavarian Academy of Sciences and Humanities (Garching) have discovered previously unknown metallic features of high-temperature superconductors by running meticulously precise measurements. The results, recently presented in the Physical Review Letters journal ("Evolution of the Fermi Surface of the Electron-Doped High-Temperature Superconductor Nd2-xCexCuO4 Revealed by Shubnikov–de Haas Oscillations"), have met with a remarkable response in the scientific community.
The High-Magnetic Field Laboratory Dresden provides highly pulsed magnetic fields of up to 70 Tesla reliably for research purposes and hence has gained a positive reputation with researchers from all over the world. This time, the guests were from Bavarian Garching. Prof.Rudolf Gross’ research group brought optimally prepared samples of cuprate – a compound containing copper, oxygen and other elements – to Dresden, aiming at finally either confirming or disproving the inconsistent theoretical notions of high-temperature superconductors.
The scientific community has been waiting about 20 years for those measurements, as highly magnetic fields over 60 Tesla combined with sophisticated methods of investigation at optimally equippedl aboratories have only recently come into existence within Europe in Dresden.
Those highly magnetic fields are inevitable when it comes to high-temperature superconductors, for they enable suppression of superconductivity at low temperatures and thorough investigation in the state of normal conductance. As discovered more than 20 years ago, these substances losslessly conduct electricity at relatively high temperatures, in the easily accessible span between -150 to -200 degrees C°. Thus, they are foretold a great future in technology, despite the lack of elementary understanding. Without this, however, asystematic application for high technology will hardly be realistic.
The physicists from Garching and Dresden were able to add another unit to basic understanding of high-temperature superconductors. In the magnetic field laboratory it was discovered that superconductors behave quite differently from what was expected in the normal conductive state with suppressed superconductivity. This unique metallic state is at the same time the fundamental problem to be understood and solved.
An entirely new light is being shed on the dominating theorie sconcerning the nature of superconductivity in doped high-temperature superconductors.
Yet, further research is to be conducted in order to understanding howexactly the metallic, superconducting and magnetic characteristics interdepend.
Also, the physicists are hoping for information on the exact nature of the changeovers from normal to superconductive states. Only then it will be possible to produce customized high-temperature superconductors for broad technological use.
Source: Kompetenznetze Deutschland
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