Featured Research

from universities, journals, and other organizations

New Insight Into Origin Of Superconductivity In Magnesium Diboride

Date:
June 19, 2002
Source:
Brookhaven National Laboratory
Summary:
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.

UPTON, NY -- 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 MgB2 arises from interactions between holes. Also, because MgB2 is 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, MgB2 has 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 MgB2 sample," 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.

The U.S. Department of Energy's Brookhaven National Laboratory (http://www.bnl.gov) conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies. Brookhaven also builds and operates major facilities available to university, industrial, and government scientists. The Laboratory is managed by Brookhaven Science Associates, a limited liability company founded by Stony Brook University and Battelle, a nonprofit applied science and technology organization.


Story Source:

The above story is based on materials provided by Brookhaven National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Brookhaven National Laboratory. "New Insight Into Origin Of Superconductivity In Magnesium Diboride." ScienceDaily. ScienceDaily, 19 June 2002. <www.sciencedaily.com/releases/2002/06/020618072205.htm>.
Brookhaven National Laboratory. (2002, June 19). New Insight Into Origin Of Superconductivity In Magnesium Diboride. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2002/06/020618072205.htm
Brookhaven National Laboratory. "New Insight Into Origin Of Superconductivity In Magnesium Diboride." ScienceDaily. www.sciencedaily.com/releases/2002/06/020618072205.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins