Skip to comments.High-temperature superconductor spills secret: A new phase of matter
Posted on 03/25/2011 3:27:53 PM PDT by decimon
(PhysOrg.com) -- Scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have joined with researchers at Stanford University and the SLAC National Accelerator Laboratory to mount a three-pronged attack on one of the most obstinate puzzles in materials sciences: what is the pseudogap?
A collaboration organized by Zhi-Xun Shen, a member of the Stanford Institute for Materials and Energy Science (SIMES) at SLAC and a professor of physics at Stanford University, used three complementary experimental approaches to investigate a single material, the high-temperature superconductor Pb-Bi2201 (lead bismuth strontium lanthanum copper-oxide). Their results are the strongest evidence yet that the pseudogap phase, a mysterious electronic state peculiar to high-temperature superconductors, is not a gradual transition to superconductivity in these materials, as many have long believed. It is in fact a distinct phase of matter.
"This is a paradigm shift in the way we understand high-temperature superconductivity," says Ruihua He, lead author with Makoto Hashimoto of the paper in the March 25 issue of the journal Science that describes the team's findings. "The involvement of an additional phase, once fully understood, might open up new possibilities for achieving superconductivity at even higher temperatures in these materials." When the research was done Hashimoto and He were members of SIMES, of Stanford's Department of Applied Physics, and of Berkeley Lab's Advanced Light Source (ALS), where He is now a postdoctoral fellow.
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Kinetic on pseudogap ping.
My labradoodle eats pseudogaps.
When did lead bismuth strontium lanthanum copper-oxide become a single material?
When the dish ran away with the spoon? Beats me.
Just another alloy, with interesting electrical properties.
Right after the divorce
hehe he heh.. heh.. He said ‘kinetic’ heh.. heh.. he hehe.
Makes sense it would be, I think.
How could it superconduct unless it had all it’s ducks in a row?
“When did lead bismuth strontium lanthanum copper-oxide become a single material? “
Like yttrium barium copper oxide, (YBa2Cu3O7-x), it is an oxide containing several metal ions. Each one must be given in the name.
I should have added, yttrium barium copper oxide was the first high temperature superconductor to exhibit superconductivity above the boiling point of liquid nitrogen (T=77K, -196C). It goes superconducting at 93K (-180C).
The key ingredient in the High Tc materials are naturally-ocurring 2-dimensional substrates of CO2.
The High Tc materials are “Jahn-Teller distort materials” - which simply mean that they contain these stable sheets of CO2. Playing around with the other materials changes the hole-doping of the CO2.
Antiferromagnetic exchange between hole-pairs acts as an attractive force between hole pairs on this sort of lattice, but it doesn’t by itself beat charge repulsion.
I left the field before the correct pairing mechanism was identified - if it has indeed yet been identified. The leading theory (IIRC) of the hole-pairing involved not pairing, but collective behaviour due to the fractional quantum Hall effect which can only occur on 2-and-a-bit-dimensional lattices such as these JT-distort lattices.
Do you happen to know what the critical magnetic field is on the YBa2Cu3O7-x family?
What I really want to know is the supportable current density. Does a temp lower than 77K help in this regard?
IIRC about 100 T. The critical current depends on direction relative to the CUO2 plane.
Ouch, after midnight. Goodnight all.
three complementary experimental approaches to investigate a single material, the high-temperature superconductor Pb-Bi2201 (lead bismuth strontium lanthanum copper-oxide)... are the strongest evidence yet that the pseudogap phase, a mysterious electronic state peculiar to high-temperature superconductors, is not a gradual transition to superconductivity in these materials, as many have long believed. It is in fact a distinct phase of matter.Pb stands for Pepto-Bismol, and this research isn't done with its investigation of antacids.
Solid, Liquid, Gas, Plasma, and Superconductivity?
That sounds like a whole lotta current density.
But then again, I haven’t had to do that calculation since MetEng 221 (or was it Phys 363?) in 1968.
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