Superconductivity: Which one of these is not like the other?

Jul 13, 2009
Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors. Credit: American Physical Society [Illustration: Alan Stonebraker]

Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors. The insight comes from research groups that are making bold statements about the correct description of superconductivity in iron-based compounds in two papers about to be published in journals of the American Physical Society.

The 2008 discovery of in iron-based compounds has led to a flood of research in the past year. As the literature mounts on these materials, which superconduct at temperatures as high as 55 K, two key questions are emerging: Is the origin of superconductivity in all of the iron-based compounds the same and are these materials similar to the copper oxide-based high-temperature superconductors (commonly known as cuprates), which physicists have studied for nearly twenty years but are still unable to explain with a complete theory?

These questions are addressed separately in two papers highlighted in the July 13 issue of Physics. A collaboration between scientists at Lawrence Berkeley National Lab, the SLAC National Accelerator Laboratory, Stanford University and institutions in Switzerland, China, Mexico and the Netherlands reports in Physical Review B x-ray experiments indicating that, in iron-based superconductors that contain arsenic or phosphorous (called 'iron pnictides'), the electrons that ultimately pair to form the superconducting state behave differently than those in the cuprates. More specifically, while the electrons in the cuprates are strongly correlated - meaning the energy of one electron is tied to the energy of the others - the electrons in the iron-pnictide superconductors behave more like those of a normal metal in which the electrons do not (to first approximation) interact.

In a paper appearing in , scientists at Princeton, UC Berkeley and Shanghai Jiao Tong University in China present the first photoemission measurements on an iron-based superconductor that contains tellurium, Fe1+xTe. They argue the origin of superconductivity in this type of iron compound, which belongs to a class of materials called the iron-chalcogenides, has a different origin than in the arsenic and phosphorous containing iron-pnictides. In fact, the measurements suggest that in the iron-chalcogenides may be more similar to that of the cuprates.

The statements put forth in these two articles are likely to influence the direction taken by physicists who work on the theory of iron-based . See the Viewpoint article in the July 13 issue of APS Physics to learn more.

More information: physics.aps.org/

Source: American Physical Society

Explore further: New microscope collects dynamic images of the molecules that animate life

add to favorites email to friend print save as pdf

Related Stories

New theory for latest high-temperature superconductors

Aug 13, 2008

Physicists from Rice and Rutgers universities have published a new theory that explains some of the complex electronic and magnetic properties of iron "pnictides." In a series of startling discoveries this spring, pnictides ...

Physicists offer new theory for iron compounds

Mar 12, 2009

An international team of physicists from the United States and China this week offered a new theory to both explain and predict the complex quantum behavior of a new class of high-temperature superconductors.

Putting the Pressure on Iron-Based Superconductors

Mar 05, 2009

(PhysOrg.com) -- Traditionally, magnetism and superconductivity don't mix. For more than 20 years, the only known superconductors that worked at so-called "high" temperatures (above 30 K, or about -406 degrees ...

Recommended for you

Cooling with molecules

Oct 22, 2014

An international team of scientists have become the first ever researchers to successfully reach temperatures below minus 272.15 degrees Celsius – only just above absolute zero – using magnetic molecules. ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Nik_2213
not rated yet Jul 13, 2009
The more variations, the merrier...

Perhaps a 'pattern' will emerge.
gmurphy
not rated yet Jul 13, 2009
my new favourite word : pnictides, ;-), but on a serious note, I agree with with Nik
Slotin
Jul 13, 2009
This comment has been removed by a moderator.