Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Superconductivity without cooling

03.12.2014

An infrared laser pulse briefly modifies the structure of a high-temperature superconductor and thus removes its electrical resistance even at room temperature

Superconductivity is a remarkable phenomenon: superconductors can transport electric current without any resistance and thus without any losses whatsoever. It is already in use in some niche areas, for example as magnets for nuclear spin tomography or particle accelerators. However, the materials must be cooled to very low temperatures for this purpose.


No resistance at room temperature: The resonant excitation of oxygen oscillations (blurred) between CuO2 double layers (light blue, Cu yellowy orange, O red) with short light pulses leads to the atoms in the crystal lattice briefly shifting away from their equilibrium positions. This shift brings about an increase in the separations of CuO2 layers within a double layer and a simultaneous decrease in the separations between double layers. It is highly probable that this enhances the superconductivity.

© Jörg Harms/MPI for the Structure and Dynamics of Matter

But during the past year, an experiment has provided some surprise. With the aid of short infrared laser pulses, researchers have succeeded for the first time in making a ceramic superconducting at room temperature – albeit for only a few millionths of a microsecond. An international team, in which physicists from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg have made crucial contributions, has now been able to present a possible explanation of the effect in the journal Nature:

The scientists believe that laser pulses cause individual atoms in the crystal lattice to shift briefly and thus enhance the superconductivity. The findings could assist in the development of materials which become superconducting at significantly higher temperatures and would thus be of interest for new applications.

In the beginning, superconductivity was known only in a few metals at temperatures just above absolute zero at minus 273 degrees Celsius. Then, in the 1980s, physicists discovered a new class, based on ceramic materials. These already conduct electricity at temperatures of around minus 200 degrees Celsius without losses, and were therefore called high-temperature superconductors.

One of these ceramics is the compound yttrium barium copper oxide (YBCO). It is one of the most promising materials for technical applications such as superconducting cables, motors and generators.

The YBCO crystal has a special structure: thin double layers of copper oxide alternate with thicker intermediate layers which contain barium as well as copper and oxygen. The superconductivity has its origins in the thin double layers of copper dioxide. This is where electrons can join up to form so-called Cooper pairs. These pairs can “tunnel” between the different layers, meaning they can pass through these layers like ghosts can pass through walls, figuratively speaking – a typical quantum effect.

The crystal only becomes superconducting below a “critical temperature”, however, as only then do the Cooper pairs tunnel not only within the double layers, but also “spirit” through the thicker layers to the next double layer. Above the critical temperature, this coupling between the double layers is missing, and the material becomes a poorly conducting metal.

The result helps material scientists to develop new superconductors

In 2013, an international team working with Max Planck researcher Andrea Cavalleri discovered that when YBCO is irradiated with infrared laser pulses it briefly becomes superconducting at room temperature. The laser light had apparently modified the coupling between the double layers in the crystal. The precise mechanism remained unclear, however – until the physicists were able to solve the mystery with an experiment at the LCLS in the US, the world’s most powerful X-ray laser.

“We started by again sending an infrared pulse into the crystal, and this excited certain atoms to oscillate,” explains Max Planck physicist Roman Mankowsky, lead author of the current Nature study. “A short time later, we followed it with a short X-ray pulse in order to measure the precise crystal structure of the excited crystal.”

The result: The infrared pulse had not only excited the atoms to oscillate, but had also shifted their position in the crystal as well. This briefly made the copper dioxide double layers thicker - by two picometres, or one hundredth of an atomic diameter - and the layer between them became thinner by the same amount. This in turn increased the quantum coupling between the double layers to such an extent that the crystal became superconducting at room temperature for a few picoseconds.

On the one hand, the new result helps to refine the still incomplete theory of high-temperature superconductors. “On the other, it could assist materials scientists to develop new superconductors with higher critical temperatures,” says Mankowsky. “And ultimately to reach the dream of a superconductor that operates at room temperature and needs no cooling at all.”

Until now, superconducting magnets, motors and cables must be cooled to temperatures far below zero with liquid nitrogen or helium. If this complex cooling were no longer necessary, it would mean a breakthrough for this technology.


Contact


Prof. Dr. Andrea Cavalleri
Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
Phone: +49 40 8998-5354

Email: andrea.cavalleri@mpsd.mpg.de

Dr. Michael Först
Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
Phone: +49 40 8998-5360

Fax: +49 40 8998-1958

Email: michael.foerst@mpsd.cfel.de

Roman Mankowsky
Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
Phone: +49 40 8998-6261

Email: roman.mankowsky@mpsd.mpg.de


Original publication
R. Mankowsky, A. Subedi, M. Först, S. O. Mariager, M. Chollet, H. T. Lemke, J. S. Robinson, J. M. Glownia, M. P. Minitti, A. Frano, M. Fechner, N. A. Spaldin, T. Loew, B. Keimer, A. Georges & A. Cavalleri

Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5

Nature, 4 December 2014; doi:10.1038/nature13875

Prof. Dr. Andrea Cavalleri | Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
Further information:
http://www.mpg.de/8785897/superconductivity-room-temperature

More articles from Materials Sciences:

nachricht Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University

nachricht 3D-Printing: Support structures to prevent vibrations in post-processing of thin-walled parts
12.07.2018 | Fraunhofer-Institut für Produktionstechnologie IPT

All articles from Materials Sciences >>>

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

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

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>