Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Insight Into Origin of Superconductivity in Magnesium Diboride

18.06.2002


A team of scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, the U.S. Department of Commerce’s National Institute of Standards and Technology (NIST), and the University of Oslo in Norway has provided new insight into the superconductivity of magnesium diboride (MgB2), an unusual superconductor discovered only last year. The new result appears in the June 17, 2002 issue of Physical Review Letters.



Understanding the origin of superconductivity — the ability of some materials to conduct electricity without losing energy — will help scientists improve magnetic resonance imaging (MRI) and the efficiency of electric power transmission, and build smaller, more powerful electronic devices.

Scientists usually assume that superconductivity arises from electrons coupling in pairs,” said Yimei Zhu, a physicist at Brookhaven’s Advanced Electron Microscopy Facility and lead author of the study. “Though this is the case for most superconductors, it has not been shown yet how electrons contribute to superconductivity in magnesium diboride. So we decided to look more closely at this material’s electronic structure.”


Since the discovery of superconductivity in MgB2, Brookhaven theoretical scientists led by physicists James Davenport and Guenter Schneider have made extensive calculations involving interactions between electrons or between electron “holes,” which are empty locations that could be filled by electrons. According to one of the most prevalent theories, superconductivity in MgB2arises from interactions between holes. Also, because MgB2is made of alternating planes of boron and magnesium atoms aligned parallel to one another, these holes are expected to interact more easily within the planes than between adjacent planes.

Compared to other superconductors, MgB2has a relatively simple structure,” said Johan Tafto, a physicist at the University of Oslo and one of the team members. “So scientists hope to get more insight into superconductivity by focusing their attention on a simple compound rather than on more complex ones.”

To test the theoretical predictions about MgB2, the scientists examined the electron and hole structure of the substance using two complementary techniques. In the first technique, called x-ray absorption spectroscopy, the scientists used very intense x-rays generated by the National Synchrotron Light Source (NSLS) at Brookhaven and a unique NIST x-ray detector. When the x-rays enter the sample, the electrons inside the sample absorb the x-rays and are ejected out of their original positions.

“When these ejected electrons fall into the holes, they reveal the number and density of these holes in the MgB2sample,” said Daniel Fischer, a physicist at NIST who has been working with the x-ray absorption technique for the last 18 years at the NSLS.

The second technique, called electron energy loss spectroscopy, uses state-of-the-art transmission electron microscopes (TEMs) at Brookhaven. Unlike optical microscopes, which use visible light, an electron microscope projects electrons toward the sample. These electrons transfer some of their energy to electrons in the sample, which bump around the sample atoms and reveal the positions of electronic holes in the MgB2 sample.

“We needed to use both techniques because they complement each other very well and lead to a very accurate determination of the distribution and number of electron holes in magnesium diboride,” said Zhu, who leads Brookhaven’s TEM group and has been investigating the electronic structure of materials at the nanoscale (one billionth of a meter) for the last 20 years.

The results agree with the theoretical predictions by showing that interactions between holes in the boron planes do occur in MgB2, and that superconductivity stems from such interactions. Said Tafto, “As we gain more understanding of the properties of magnesium diboride at the atomic level, I am confident that, in the near future, we will be able to relate them to macroscopic properties such as superconductivity — and maybe explain the origin of superconductivity in general.”

This work was funded by the U.S. Department of Energy, which supports basic research in a variety of scientific fields, and the U.S. Department of Commerce

Karen McNulty Walsh | EurekAlert!

More articles from Physics and Astronomy:

nachricht The moon is front and center during a total solar eclipse
24.07.2017 | NASA/Goddard Space Flight Center

nachricht Superluminous supernova marks the death of a star at cosmic high noon
24.07.2017 | Royal Astronomical Society

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: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Ultrathin device harvests electricity from human motion

24.07.2017 | Power and Electrical Engineering

Scientists announce the quest for high-index materials

24.07.2017 | Materials Sciences

ADIR Project: Lasers Recover Valuable Materials

24.07.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>