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 Fast flowing heat in layered material heterostructures
18.12.2017 | Graphene Flagship

nachricht One in 5 materials chemistry papers may be wrong, study suggests
15.12.2017 | Georgia Institute of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Error-free into the Quantum Computer Age

A study carried out by an international team of researchers and published in the journal Physical Review X shows that ion-trap technologies available today are suitable for building large-scale quantum computers. The scientists introduce trapped-ion quantum error correction protocols that detect and correct processing errors.

In order to reach their full potential, today’s quantum computer prototypes have to meet specific criteria: First, they have to be made bigger, which means...

Im Focus: Search for planets with Carmenes successful

German and Spanish researchers plan, build and use modern spectrograph

Since 2016, German and Spanish researchers, among them scientists from the University of Göttingen, have been hunting for exoplanets with the “Carmenes”...

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

The body's street sweepers

18.12.2017 | Life Sciences

Fast flowing heat in layered material heterostructures

18.12.2017 | Materials Sciences

Life on the edge prepares plants for climate change

18.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>