Featured Research

from universities, journals, and other organizations

Study may explain variations in superconducting temperatures

Date:
May 14, 2008
Source:
Cornell University
Summary:
New experiments have verified a theory that variations in the distance between atoms in cuprate superconductors account for differences in the temperature at which the material begins to superconduct. A better understanding of the process could lead to superconductors that work at higher temperatures.

Cuprate crystals consist of layers of copper oxide interleaved with layers of other atoms. Copper and oxygen atoms usually form a pyramid with the oxygen atom at the apex located in an adjacent layer. Cornell research now shows that other atoms pushing that oxygen out of position creates superconductivity.
Credit: Davis Lab / Courtesy of Cornell University

New experiments at Cornell have verified a theory that variations in the distance between atoms in cuprate superconductors account for differences in the temperature at which the material begins to superconduct. A better understanding of the process could lead to superconductors that work at higher temperatures.

Related Articles


The research is reported in the March 4 issue of the Proceedings of the National Academy of Sciences.

Superconductors are materials that conduct electricity with virtually no resistance. While many superconductors work only at temperatures within a few degrees of absolute zero and must be cooled with liquid helium, a class of copper oxides known as cuprates, containing "dopant" atoms of other elements in addition to copper and oxygen, superconduct at temperatures ranging from 26 to 148 Kelvin (-248 to -125 Celsius) and can be cooled with less expensive liquid nitrogen. But no one has explained the wide variation in superconducting temperatures, which vary with the combinations of impurities added to the copper oxide.

Within most cuprate crystals, the copper and oxygen atoms are arranged in pyramids, with an oxygen atom at the apex. Theorists have proposed that superconductivity can be modified when dopants alter the crystal structure and push this apex-atom down or sideways, changing the way its electrons interact with those in the atoms in the pyramid base.

To test this idea, a Cornell team led by James Slezak, a graduate student working with J.C. Séamus Davis, Cornell professor of physics, studied a cuprate whose crystal structure varies in repeating waves across the crystal. Using a scanning tunneling microscope that can resolve subatomic distances, the researchers compared a physical image that showed the periodic rising and falling distances between atoms in the crystal with electrical signals that represent the pairing of electrons. Indeed, electron pairing was stronger in places where the oxygen atom was squeezed down. Theory says that superconductivity happens when electrons join into pairs that can move through the crystal more freely than single electrons.

"This proves that gluing the pairs together is a property of each crystal unit cell, not an overall property of the material," Davis said.

The researchers also verified that electron pairing is more likely in the vicinity of dopant atoms, at completely random locations in the crystal. Both effects are taking place at the same time, Davis said, and both result from the squeezing of the copper-oxide pyramid. "You don't need two different explanations," he said.

Co-authors of the paper include Cornell postdoctoral researcher Jinho Lee and graduate student Miao Wang as well as scientists at the University of Colorado, University of Florida, University of Copenhagen and University of Tokyo. The research was supported by the National Science Foundation, Brookhaven National Laboratory, the Office of Naval Research, the Japanese Ministry of Science and Education and the Japan Society for the Promotion of Science.


Story Source:

The above story is based on materials provided by Cornell University. The original article was written by Bill Steele. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. A. Slezak, J. Lee, M. Wang, K. McElroy, K. Fujita, B. M. Andersen, P. J. Hirschfeld, H. Eisaki, S. Uchida, J. C. Davis. Imaging the impact on cuprate superconductivity of varying the interatomic distances within individual crystal unit cells. Proceedings of the National Academy of Sciences, 2008; 105 (9): 3203 DOI: 10.1073/pnas.0706795105

Cite This Page:

Cornell University. "Study may explain variations in superconducting temperatures." ScienceDaily. ScienceDaily, 14 May 2008. <www.sciencedaily.com/releases/2008/05/080512213306.htm>.
Cornell University. (2008, May 14). Study may explain variations in superconducting temperatures. ScienceDaily. Retrieved April 24, 2015 from www.sciencedaily.com/releases/2008/05/080512213306.htm
Cornell University. "Study may explain variations in superconducting temperatures." ScienceDaily. www.sciencedaily.com/releases/2008/05/080512213306.htm (accessed April 24, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, April 24, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Food Printing: The Meal of the Future?

3D Food Printing: The Meal of the Future?

AP (Apr. 23, 2015) — Developers of 3D food printing hope the culinary technology will revolutionize the way we cook and eat. (April 23) Video provided by AP
Powered by NewsLook.com
'Safest Bike Ever' Devised by British Entrepreneur

'Safest Bike Ever' Devised by British Entrepreneur

Reuters - Innovations Video Online (Apr. 23, 2015) — A British inventor says his Babel bike is the safest bicycle ever produced. Crispin Sinclair - son of famous British inventor Sir Clive Sinclair - hopes the bike&apos;s safety cage, double seatbelt, and host of other measures will inspire non-cyclists to get in the saddle. Jim Drury went to see it in action. Video provided by Reuters
Powered by NewsLook.com
First Successful Aerial Refueling of a Drone

First Successful Aerial Refueling of a Drone

Reuters - Innovations Video Online (Apr. 23, 2015) — The bat-wing U.S. Navy drone that became the first autonomous airplane to take off and land on an aircraft carrier accomplished yet another milestone on Wednesday, becoming the first unmanned aircraft to undergo aerial refueling. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Human or Robot You Decide

Human or Robot You Decide

Reuters - Business Video Online (Apr. 23, 2015) — An ultra-realistic humanoid robot called &apos;Han&apos; recognises and interprets people&apos;s facial expressions and can even hold simple conversations. Developers Hanson Robotics hope androids like Han could have uses in hospitality and health care industries where face-to-face communication is vital. Matthew Stock reports. Video provided by Reuters
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:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

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