Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print More evidence for 'stripes' in high-temperature superconductors

More evidence for 'stripes' in high-temperature superconductors

April 27, 2006

Supports earlier controversial finding, may help explain superconducting mechanism
UPTON, NY - An international collaboration including two physicists from the U.S. Department of Energy's Brookhaven National Laboratory has published additional evidence to support the existence of "stripes" in high-temperature (Tc) superconductors. The report in the April 27, 2006, issue of Nature strengthens earlier claims that such stripes - a particular spatial arrangement of electrical charges - might somehow contribute to the mechanism by which these materials carry current with no resistance. Understanding the mechanism for high-Tc superconductors, which operate at temperatures warmer than traditional superconductors but still far below freezing, may one day help scientists design superconductors able to function closer to room temperature for applications such as more-efficient power transmission.

In the material the scientists studied, as in all materials, the atoms' negatively charged electrons repel one another. But by trying to stay as far apart as possible, each individual electron is confined to a limited space, which makes the electrons "unhappy" in the sense that it costs energy. "It's like putting a bunch of claustrophobics into a crowded room," says Brookhaven physicist John Tranquada, who leads the Lab's role in this work.




To achieve a lower-energy state, the electrons arrange themselves with their spins aligned in alternating directions on adjacent atoms, a configuration known as antiferromagnetic order. Through chemical substitutions, the scientists can effectively "dope" the material with electron "holes," or the absence of electrons, to allow the electrons/holes to move more freely and carry current as a superconductor.

The big question is: How do those electrons/holes arrange themselves?

"Our earlier research suggests that the holes segregate themselves into stripes that alternate with antiferromagnetic regions," Tranquada says. Their conclusion is based on observing a similar magnetic signature in a well-known high-Tc superconductor and a material known to have such charge-segregated stripes. Ironically, the stripes in the latter material are observable only at a particular level of doping where the material loses its superconductivity. But because the magnetic spectra were so similar, Tranquada says, "We inferred that the stripes might also be present in the superconducting materials, just more fluid, or dynamic - and harder to observe."

Since then, Tranquada's group has been looking for additional experimental signatures to back up their controversial claim. In the current experiment, they examined the effect of the stripes on vibrations in the crystal lattice. Lattice vibrations, or phonons, are known to play a role in pairing up the electrons that carry current in conventional superconductors.

At the Laboratorie Leon Brillouin, Saclay, in France, the researchers bombarded samples of superconducting materials and the same stripe-ordered non-superconductor with beams of neutrons and measured how the beams scattered. Comparing the energy and momentum of the incoming beams with those scattered by the samples gives the scientists a measure of how much energy and momentum is transferred to the lattice vibrations.

Each of these vibrations, like a vibrating guitar string, normally has a particular, well-defined frequency for a given wavelength. But in the superconductor experiment, at a particular wavelength, the scientists observed an anomaly: a wider range of frequencies in the lattice vibrations.

"It's as if a musician were able to make a single guitar string produce a chord," Tranquada says.

The scientists observed this anomalous signature most clearly in samples with observable stripe order - that is, the special material that loses its superconductivity with a particular level of doping. But they also saw it in samples of good superconductors.

"Seeing this feature in both stripe-ordered samples and in good superconductors without static stripes leads us to believe that the signature is indicating the presence of dynamic stripes," Tranquada says.

"This result suggests that stripes are common to copper-oxide superconductors and may be important in the mechanism for high-Tc superconductivity," he adds. To further support their case, Tranquada notes that the anomalous signature goes away in cases where the superconducting material is either under- or over-doped. In this case, the material no longer acts as a superconductor, and may no longer have stripes, he says.

DOE/Brookhaven National Laboratory



Related Superconductors Current Events and Superconductors News Articles Superconductors Current Events and Superconductors News RSS Superconductors Current Events and Superconductors News RSS
New study confirms exotic electric properties of graphene
First, it was the soccer-ball-shaped molecules dubbed buckyballs. Then it was the cylindrically shaped nanotubes. Now, the hottest new material in physics and nanotechnology is graphene: a remarkably flat molecule made of carbon atoms arranged in hexagonal rings much like molecular chicken wire.

Quantum gas microscope offers glimpse of quirky ultracold atoms
Physicists at Harvard University have created a quantum gas microscope that can be used to observe single atoms at temperatures so low the particles follow the rules of quantum mechanics, behaving in bizarre ways.

Putting a Strain on Nanowires Could Yield Colossal Results
In finally answering an elusive scientific question, researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have shown that the selective placement of strain can alter the electronic phase and its spatial arrangement in correlated electron materials.

Atoms don't dance the 'bose nova'
Hanns-Christoph Naegerl's research group has investigated how ultracold quantum gases behave in lower spatial dimensions. They successfully realized an exotic state, where, due to the laws of quantum mechanics, atoms align along a one-dimensional structure.

Scientists detect 'fingerprint' of high-temp superconductivity above transition temperature
A team of U.S. and Japanese scientists has shown for the first time that the spectroscopic "fingerprint" of high-temperature superconductivity remains intact well above the super chilly temperatures at which these materials carry current with no resistance.

Superconductivity: Which one of these is not like the other?
Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors.

Discovery at UAB brings us nearer to making the dream of invisibility true
A group of researchers from the Department of Physics at UAB have designed a device, called a dc metamaterial, which makes objects invisible under certain light - very low frequency electromagnetic waves - by making the inside of the magnetic field zero but not altering the exterior field.

NIST discovers how strain at grain boundaries suppresses high-temperature superconductivity
Researchers at the National Institute of Standards and Technology (NIST) have discovered that a reduction in mechanical strain at the boundaries of crystal grains can significantly improve the performance of high-temperature superconductors (HTS).

New Exotic Material Could Revolutionize Electronics
Move over, silicon-it may be time to give the Valley a new name. Physicists at the Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University have confirmed the existence of a type of material that could one day provide dramatically faster, more efficient computer chips.

Thinnest superconducting metal created
A superconducting sheet of lead only two atoms thick, the thinnest superconducting metal layer ever created, has been developed by physicists at The University of Texas at Austin.
More Superconductors Current Events and Superconductors News Articles
Economy Superconductivity Kit

Economy Superconductivity Kit
by Arbor Scientific

Our superconductivity kit features a large superconductive disc formulated from the oxides of Yttrium, Barium, and Copper in the famous 1-2-3 chemical combination. The disc has a critical temperature of 92 degrees Kelvin. Chill the disc to 77 degrees Kelvin with liquid nitrogen and it produces a striking Meissner Effect (magnetic levitation) when the neodymium magnet is introduced. Kit Includes: One Super Conductive Disc (1" dia. x 1/8") One Neodymium Magnet (1/8" dia. x 1/8") One Petri Dish Cover Low Temperature Plastic Forceps Instructions & Safety Precautions

Introduction to Superconductivity: Second Edition (Dover Books on Physics) (Vol i)

Introduction to Superconductivity: Second Edition (Dover Books on Physics) (Vol i)
by Michael Tinkham (Author)

Accessible to graduate students and experimental physicists, this volume emphasizes physical arguments and minimizes theoretical formalism. Topics include  the Bardeen-Cooper-Schrieffer and Ginzburg-Landau theories, magnetic properties of classic type II superconductors, the Josephson effect, fluctuation effects in classic superconductors, high-temperature superconductors, and nonequilibrium superconductivity. 109 figures. 1996 edition.

Hit Songs for Girls

Hit Songs for Girls
by Superconductor



Voltage Superconductor

Voltage Superconductor
by Voltage Security, Inc.

If you are interested in the underpinnings of enterprise security, cryptography or how security and usability are intimately connected - this blog will make you happyKindle blogs are fully downloaded onto your Kindle so you can read them even when you're not wirelessly connected. And unlike RSS readers which often only provide headlines, blogs on Kindle give you full text content and images, and are updated wirelessly throughout the day.

2.5 cu. ft. Superconductor Refrigerator

2.5 cu. ft. Superconductor Refrigerator
by Avanti

The Avanti Superconductor Refrigerator - White (model: SHP1700W) provides 1.7 cubic feet of refrigeration capacity with quiet thermoelectric cooling technology. The unit uses R134A refrigerant, but has no compressor, allowing quiet operation while performing as efficiently as a compressor would, while featuring auto-defrosting technology. You get all the functionality you deserve, with all the features you would expect in a premium refrigerator. It has an adjustable thermostat, an interior LED light, a reversible door, and the door shelf even fits a 2 liter bottle! Key Features: High Efficiency Solid State Components of Superior Reliability No Vibration Unique State-of-the-Art Thermoelectric Technology Environmentally Friendly Full Range Temperature Control Reversible Door - Left or Right...

Avanti White Compact SUPERCONDUCTOR Refrigerator

Avanti White Compact SUPERCONDUCTOR Refrigerator
by Avanti

Avanti White Compact SUPERCONDUCTOR Refrigerator - SHP1700WH. 1.7 Cu. Ft. Capacity. Thermoelectric Technology. Full Range Temperature Control. Slide-Out Shelf. Environmentally Friendly. Reversible Door. White Finish

Complete Superconductivity Kit

Complete Superconductivity Kit
by Arbor Scientific

Our superconductivity kit features a large superconductive disc formulated from the oxides of Yttrium, Barium, and Copper in the famous 1-2-3 chemical combination. The disc has a critical temperature of 92 degrees Kelvin. Chill the disc to 77 degrees Kelvin with liquid nitrogen and it produces a striking Meissner Effect (magnetic levitation) when the neodymium magnet is introduced. Kit Includes: One Super Conductive Disc (1" dia. x 1/8") One Neodymium Magnet (1/8" dia. x 1/8") One Petri Dish Cover Low Temperature Plastic Forceps One Thermos container, Gloves & Goggles Instructions & Safety Precautions

Hit Songs for Girls

Hit Songs for Girls
Superconductor (Primary Contributor)



  SciEd Basic Superconductivity Levitation Kit; Complete Demonstration Kit
by Colorado Superconductor

Kit, Basic Superconductivity Levitation, demonstrates Meissner Effect and Low Friction Magnetic Bearings

  Chemistry of High-Temperature Superconductors (Acs Symposium Series) (Vol 1)
by David L. Nelson (Author), M. Stanley M. Whittingham (Author), Thomas F. George (Editor)



© 2009 BrightSurf.com