Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

‘Virtual’ reality check for superconductors

13.02.2008
Researchers at RIKEN’s Discovery Research Institute in Wako, in collaboration with researchers from Cornell University in the US, and Kyoto University, have refined a method that measures small electronic excitations in superconductors.

New clues important to our understanding of superconductivity are provided by precise measurements of electronic states

Researchers at RIKEN’s Discovery Research Institute in Wako, in collaboration with researchers from Cornell University in the US, and Kyoto University, have refined a method that measures small electronic excitations in superconductors. Comparisons of these properties for different materials have provided valuable clues towards our understanding of superconductivity.

The classical theory of superconductivity describes the superconducting state arising through the pairing of electrons into pairs. The properties of these electron pairs, however, are difficult to model mathematically. Physicists therefore prefer to describe them as a virtual single ‘quasiparticle’. “Although these quasiparticles are fictitious, they really govern the electronic states of superconductors, particularly at low energies,” explains Tetsuo Hanaguri from the research team.

Many details of the electronic states of quasiparticles and the precise amount of energy it takes to break up the electron pairs are difficult to measure, and remain poorly understood. This ‘break-up energy’, referred to as the ‘superconducting gap’, is traditionally considered as being directly related to the critical temperature where superconductivity persists. The larger the gap, the greater the difficultly to break up the electron pairs, thus the higher the critical temperature is for superconductivity. However, this relation has never been confirmed for the so-called ‘high-temperature’ superconductors, whose mechanism of superconductivity remains a mystery.

Reporting in the journal Nature Physics1, the RIKEN researchers have now measured the properties of the quasiparticles using a scanning tunneling microscope that scans the surface of a superconducting material with an atomic resolution and records tiny variations in the electronic structure. However, the observed periodic variations in the electronic properties are difficult to analyze as a number of effects contribute to these regular patterns. Therefore, Hanaguri and colleagues developed a novel mathematical technique to successfully pick out the quasiparticle signatures.

This mathematical technique allows the researchers to characterize several materials and compare their superconducting properties. Surprisingly, the relative variation in the superconducting gap was found to be the same for two different high-temperature superconductors, although their critical temperature differs by a factor of three. This shows that, contrary to conventional assumptions, the superconducting state is influenced by more than just the size of the superconducting gap.

To better understand the relation between superconducting gap and superconductivity, Hanaguri says that further measurements are needed to determine the effect of temperature and magnetic field on the quasiparticles. Ultimately, these measurements may provide vital clues on the fundamental mechanisms governing high-temperature superconductors.

1. Hanaguri, T., Kohsaka, Y., Davis, J. C., Lupien, C., Yamada, I., Azuma, M., Takano, M., Ohishi, K., Ono, M. & Takagi, H. Quasiparticle interference and superconducting gap in Ca2–xNaxCuO2Cl2. Nature Physics 3, 865–871 (2007).

Saeko Okada | ResearchSEA
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Power and Electrical Engineering:

nachricht A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes
20.07.2018 | Science China Press

nachricht Future electronic components to be printed like newspapers
20.07.2018 | Purdue University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

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....

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

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>