Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > New superconductivity mechanism found in iron compound

STM scan showing a 96-nanometer square of an iron-based superconductor shows electrons lined up in parallel rows suggesting a 'liquid-crystal' state of the electron fluid. The parallel arrangements appear in random domains across the entire crystal, oriented either vertically or horizontally. The diagonal line across this image is the boundary between two domains. The discovery of this arrangement indicates that the mechanism of iron-based superconductors is more complex than previously believed, and may be similar to the mechanism in cuprates.
STM scan showing a 96-nanometer square of an iron-based superconductor shows electrons lined up in parallel rows suggesting a 'liquid-crystal' state of the electron fluid. The parallel arrangements appear in random domains across the entire crystal, oriented either vertically or horizontally. The diagonal line across this image is the boundary between two domains. The discovery of this arrangement indicates that the mechanism of iron-based superconductors is more complex than previously believed, and may be similar to the mechanism in cuprates.

Abstract:
A surprising discovery by Cornell researchers of electronic liquid crystal states in an iron-based, high-temperature superconductor is another step toward understanding superconductivity and using it in such applications as power transmission.

New superconductivity mechanism found in iron compound

Ithaca, NY | Posted on January 8th, 2010

"Because these findings appear similar to what we have observed in the parent state of [copper-based] superconductors, it suggests this could represent a common factor in the mechanism for high-temperature superconductivity in these two otherwise very different families of materials," said team leader J.C. Séamus Davis, Cornell's J.D. White Distinguished Professor of Physical Sciences and director of the U.S. Department of Energy's Center for Emergent Superconductivity. The researchers describe their findings in the Jan. 8 issue of the journal Science.

Many theorists had expected the iron-based materials to act more like conventional metal superconductors, where electrons pair up to carry current effortlessly but without requiring any specific spatial arrangements of the atoms in the metal. These materials conduct electricity with zero resistance only at temperatures near absolute zero, or -270 degrees Celsius (-454 Fahrenheit).

Cuprate, or copper-based, and newly discovered iron-based superconductors operate at a range of warmer, though still chilly, temperatures (up to -120 degrees Celsius or -184 Fahrenheit for cuprates and -220 degrees Celsius or -364 Fahrenheit for iron-based compounds) that make them potentially more practical for such large-scale, real-world applications as zero-loss power transmission lines.

Cuprates are oxides of copper "doped" with various other atoms. Iron-based superconductors -- first demonstrated only in 2008 -- are mostly doped compounds of iron and arsenic. Somehow the doping distorts the crystal structure of the material in a way that makes it possible for electrons to flow without resistance. Understanding how this works could open the door to engineering even higher-temperature, or ideally, room-temperature, versions.

The scientists used a specially built scanning tunneling microscope (STM) in Davis' lab at Cornell, in which a tiny probe is moved across a surface in steps smaller than the width of an atom. By varying a current flowing between the probe and the surface, Davis is able to read out a spectrum of the energy levels of electrons in the material and produce a picture of the distribution of the electrons. Davis was recently awarded the Kamerlingh-Onnes Prize for inventing this technique.

Davis and colleagues examined "underdoped" samples of a compound of calcium, iron, cobalt and arsenic that becomes a superconductor when the amount of cobalt doping is increased. The particular material they used, made by Paul Canfield at the U.S. Department of Energy's (DOE) Ames Laboratory in Iowa, was a crucial choice, Davis said, because it could be sliced to produce an atomically flat and perfectly debris-free surface needed for the STM techniques.

It became clear to the team that they were on to something very different than expected. They observed static, nanoscale lineups of electrons spanning about eight times the distance between individual iron atoms, all aligned along one axis of the underlying crystal, reminiscent of the way molecules line up in a liquid crystal.

Liquid crystals, used in electronic displays, are a sort of intermediate state between liquid and solid in which molecules line up in parallel rows that can control the passage of light. In the solid crystals of materials like high-temperature superconductors, electrons do not remain attached to individual atoms but behave like a fluid, and here, Davis said, the electrons seem to be in a state analogous to a liquid crystal. "You can't use ordinary solid-state physics to understand materials this complicated," he said.

The scientists also found that the electrons that are free to travel through the material do so in a direction perpendicular to these aligned electronic liquid crystal states. This indicates that the electrons carrying the current are distinct from those apparently aligned in the electronic liquid crystals.

The next step will be to see how these conditions affect the superconductivity of the material when it is transformed to a superconductor.

The observations are "amazingly similar" to what Davis and his team have seen in cuprates. "If we're able to relate our observations in the iron-based superconductors to what happens in cuprate superconductors, it may help us understand the overall mechanism for high-temperature superconductivity in all of these materials. That understanding could, in turn, help us to engineer new materials with improved superconducting properties for energy applications," Davis said.

Scientists from the National High Magnetic Field Laboratory at Florida State University and St. Andrews University, Scotland, collaborated on this research, funded by DOE's Office of Science; the National Science Foundation; the Office of Naval Research; the U.K. Engineering and Physical Sciences Research Council; and the Scottish Funding Council.

Images and supplementary materials on the research are available on Davis' Web site at people.ccmr.cornell.edu/~jcdavis/

####

About Cornell University
Once called "the first American university" by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

Today's Cornell reflects this heritage of egalitarian excellence. It is home to the nation's first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

For more information, please click here

Contacts:
Media Contact:
Blaine Friedlander
(607) 254-8093


Cornell Chronicle:
Anne Ju
(607) 255-9735

Copyright © Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

SouthWest NanoTechnologies Introduces AgeNT™ Transparent Conductor System at SID Display Week, Booth #543 May 28th, 2015

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Physicists precisely measure interaction between atoms and carbon surfaces May 28th, 2015

Linking superconductivity and structure May 28th, 2015

Chemists discover key reaction mechanism behind the highly touted sodium-oxygen battery May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Discoveries

Chemists discover key reaction mechanism behind the highly touted sodium-oxygen battery May 28th, 2015

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Materials/Metamaterials

SouthWest NanoTechnologies Introduces AgeNT™ Transparent Conductor System at SID Display Week, Booth #543 May 28th, 2015

Physicists precisely measure interaction between atoms and carbon surfaces May 28th, 2015

Linking superconductivity and structure May 28th, 2015

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Announcements

Chemists discover key reaction mechanism behind the highly touted sodium-oxygen battery May 28th, 2015

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Tools

Seeing the action: UCSB researchers develop a novel device to image the minute forces and actions involved in cell membrane hemifusion May 27th, 2015

Physicists solve quantum tunneling mystery: ANU media release: An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process May 27th, 2015

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Nanometrics Announces Live Webcast of Upcoming Investor and Analyst Day May 20th, 2015

Energy

Technology for Tomorrow’s Market Opportunities and Challenges: LetiDays Grenoble Presents the Possibilities: June 24-25 Event Includes Focus on IoT-Augmented Mobility and Leti’s Latest Results on Silicon Technologies, Sensors, Health Applications and Smart Cities May 27th, 2015

Physicists solve quantum tunneling mystery: ANU media release: An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process May 27th, 2015

Fine-tuned molecular orientation is key to more efficient solar cells May 26th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project