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High-temperature superconductor 'pseudogap' imaged
Posted on Thursday, September 25, 2008 @ 22:46:53 UTC by vlad
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 By Bill Steele, Physics: Image: With the right combination of temperature (right scale) and percentage
of doping (bottom scale), a cuprate crystal becomes superconducting
(dark blue curve). As the percentage of doping decreases, a scanning
tunneling microscope image reveals some electrons flowing as waves
(shown in a Fourier diagram at lower left) and more and more electrons
locked in place in the crystal lattice (image at upper left). This
finding points the way toward higher-temperature superconductors,
researchers say. Image: Davis Lab
(PhysOrg.com) -- Cornell researchers and colleagues have produced the
first atomic-scale description of what electrons are doing in the
mysterious "pseudogap" in high-temperature superconductors.
Materials known as cuprates,
made of copper oxide doped with other atoms, can become superconducting
with just the right amount of doping, which allows electrons to bind
into pairs that can conduct electricity without interference.
"Pseudogap" refers to the fact that at some levels of doping an energy
signal for these "Cooper pairs" is found, yet the material does not
superconduct. Now Cornell experimenters find that in this state
electrons may pair up, but most of the pairs are locked into fixed
locations in the crystal lattice.
"These are the experimental observations," said J.C. Séamus Davis,
the J.G. White Distinguished Professor of Physical Sciences at Cornell
and a senior scientist at Brookhaven. "Now it's up to the theorists to
explain why it's this way." Davis and colleagues at the Brookhaven
National Laboratory and in Japan report the work in the Aug. 28 issue
of the journal Nature.
..
More: http://www.physorg.com/news141320422.html
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Unlocking the secret of the Kondo Effect (Score: 1)
by vlad on Thursday, September 25, 2008 @ 22:49:47 UTC
(User Info | Send a Message) http://www.zpenergy.com | (PhysOrg.com) -- A team of scientists including researchers from the
London Centre for Nanotechnology at UCL (University College London) and
the IBM Almaden Research Center has forged a breakthrough in
understanding an intriguing phenomenon in fundamental physics: the
Kondo effect. The findings are reported online today in the scientific
journal Nature Physics.
Full article: http://www.physorg.com/news141290015.html [www.physorg.com]
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Electron pairs precede high-temperature superconductivity (Score: 1)
by vlad on Saturday, November 08, 2008 @ 20:12:37 UTC
(User Info | Send a Message) http://www.zpenergy.com | Electron pairs precede high-temperature superconductivity
(PhysOrg.com) -- Like astronomers tweaking images to gain a more
detailed glimpse of distant stars, physicists at the U.S. Department of
Energy's (DOE) Brookhaven National Laboratory have found ways to
sharpen images of the energy spectra in high-temperature
superconductors — materials that carry electrical current effortlessly
when cooled below a certain temperature. These new imaging methods
confirm that the electron pairs needed to carry current emerge above
the transition temperature, before superconductivity sets in, but only
in a particular direction.
Full story: http://www.physorg.com/news145110552.html [www.physorg.com]
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The pseudogap persists as material superconducts (Score: 1)
by vlad on Tuesday, January 27, 2009 @ 21:11:24 UTC
(User Info | Send a Message) http://www.zpenergy.com | For nearly a century, scientists have
been trying to unravel the many mysteries of superconductivity, where
materials conduct electricity with zero resistance.
Among
the many questions: the existence of the pseudogap, a phase that up
until now was found in materials as they were cooled to temperatures
above the superconducting temperature - the phase where materials
superconduct.... More: http://www.physorg.com/news152263441.html [www.physorg.com]
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Breakthrough experiment on high-temperature superconductors (Score: 1)
by vlad on Sunday, February 22, 2009 @ 21:51:09 UTC
(User Info | Send a Message) http://www.zpenergy.com | December 12th, 2008 [www.physorg.com]
in Physics [www.physorg.com] / Physics [www.physorg.com]
The highly unusual situation shown in this plot had not been predicted by any known theoretical model.
(PhysOrg.com)
-- New information about the metallic state from which high temperature
superconductivity emerges, has been revealed in an innovative
experiment performed at the University of Bristol. The international team of physicists, led by Professor Nigel Hussey
from the University’s Physics Department, publish their results today
in Science Express, a rapid online access service for important new publications in the journal Science.
Superconductivity is a process by which a pair of electrons
travelling in opposite directions and with opposite spin direction
suddenly become attracted to one another. By pairing up, the two
electrons manage to lose all their electrical resistance. This
superconducting state means that current can flow without the aid of a
battery.
Historically, this remarkable state had always been considered a
very low temperature phenomenon, thus the origin of the
superconductivity peculiar to very unusual metallic materials termed
‘high temperature superconductors’, still remains a mystery.... More: http://www.physorg.com/news148317352.html [www.physorg.com]
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Physicists offer new theory for iron compounds (Score: 1)
by vlad on Sunday, March 15, 2009 @ 13:39:34 UTC
(User Info | Send a Message) http://www.zpenergy.com | PHYSICISTS OFFER NEW THEORY FOR IRON COMPOUNDS, March 12
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.
Full story at http://www.physorg.com/news156094850.html
[www.physorg.com]
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