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Post Info TOPIC: Superconductors


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Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon.
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Using New Tool, Scientists Uncover a Delicate Magnetic Balance for Superconductivity

A new imaging technology is giving scientists unprecedented views of the processes that affect the flow of electrons through materials.
By modifying a familiar tool in nanoscience - the Scanning Tunnelling Microscope - a team at Cornell University's Laboratory for Atomic and Solid State Physics have been able to visualise what happens when they change the electronic structure of a "heavy fermion" compound made of uranium, ruthenium and silicon. What they found sheds light on superconductivity - the movement of electrons without resistance - which typically occurs at extremely low temperatures and that researchers hope one day to achieve at something close to room temperature, which would revolutionize electronics.

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Superconductivity is a hundred years old this month, and a way to make it accessible turned 25 this week. But just how it does what it does remains a mystery even now.
Essentially, it is the property - exhibited by certain materials, often at low temperatures - to channel electrical current with zero resistance and very little power loss.

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Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon.
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Title: Spontaneous electromagnetic superconductivity of vacuum in strong magnetic field: an evidence from the Nambu--Jona-Lasinio model
Authors: M. N. Chernodub
30 Dec 2010

Using an extended Nambu--Jona-Lasinio model as a low energy effective model of QCD, we support our earlier proposal that the QCD vacuum in a strong external magnetic field (stronger than 10^{16} Tesla) experiences a spontaneous phase transition to an electromagnetically superconducting state. The unexpected superconductivity of, basically, empty space is induced by emergence of quark-antiquark vector condensates with quantum numbers of electrically charged rho mesons. The superconducting phase possesses an anisotropic inhomogeneous structure similar to a periodic Abrikosov lattice in a type-II superconductor. The superconducting vacuum is made of new type of vortices which are topological defects in the charged vector condensates. The superconductivity is realized along the axis of the magnetic field only. We argue that this effect is absent in QED.

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A new spin on superconductivity?

MIT scientists have synthesised, for the first time, a crystal they believe to be a two-dimensional quantum spin liquid: a solid material whose atomic spins continue to have motion, even at absolute zero temperature.
The crystal, known as herbertsmithite, is part of a family of crystals called Zn-paratacamites, which were first discovered in 1906. Physicists started paying more attention to quantum spin liquids in 1987, when Nobel laureate Philip W. Anderson theorised that quantum spin liquid theory may relate to the phenomenon of high-temperature superconductivity, which allows materials to conduct electricity with no resistance at temperatures above 20 degrees Kelvin (-253 degrees Celsius).

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Black holes: a model for superconductors?

Black holes are some of the heaviest objects in the universe. Electrons are some of the lightest. Now physicists at Illinois have shown how charged black holes can be used to model the behaviour of interacting electrons in unconventional superconductors.

"The context of this problem is high-temperature superconductivity. One of the great unsolved problems in physics is the origin of superconductivity (a conducting state with zero resistance) in the copper oxide ceramics discovered in 1986" - Philip Phillips, a professor of physics.

The results of research by Phillips and his colleagues Robert G. Leigh, Mohammad Edalati, and Ka Wai Lo were published online in Physical Review Letters on March 1 and in Physical Review D on February 25.

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'Broken symmetry' discovery in high-temperature superconductors opens new research path

In a major step toward understanding the mysterious "pseudogap" state in high-temperature cuprate superconductors, a team of Cornell, Binghamton University and Brookhaven National Laboratory scientists have found a "broken symmetry," where electrons act like molecules in a liquid crystal: Electrons between copper and oxygen atoms arrange themselves differently "north-south" than "east-west."
This simple discovery opens a door to new research that could lead to room-temperature superconductors.

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Hydrocarbons Can Superconduct

Superconductivity is one of those nearly magical properties that seem to defy all intuition for how the physical world ought to work. In a superconductor, electric currents flow without resistance --an electron passes unimpeded through the material like a torpedo through some frictionless ocean. After discovering the phenomenon in 1911 Dutch physicist Heike Kamerlingh Onnes showed that an electric current in a closed superconducting loop of mercury would keep flowing long after the driving potential was removed; he demonstrated his discovery by carrying such a persistent current from the Netherlands to England.
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A breakthrough approach by University of Wisconsin-Madison researchers and their collaborators in fabricating thin films of a new superconducting material has yielded promising results: The material has a current-carrying potential 500 times that of previous experiments, making it significant for a variety of practical applications.
The new approach and results appeared online in the journal Nature Materials today (Feb. 28) and illustrate a significant step forward in superconductor research.

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