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"Using a laser pulse, we drove the material out of its equilibrium state. A second, ultra-short pulse then enabled us to disentangle the components that characterise the interaction between the electrons while the material was returning to equilibrium. Metaphorically, it was like taking a series of snapshots of the different properties of that material at different moments."
Through this approach, the scientists found that "in this material, the repulsion between the electrons, and therefore their insulating properties, disappears even at room temperature. It is a very interesting observation, as this is the essential prerequisite for turning a material into a superconductor." What is the next step in achieving this? "We will be able to take this material as a starting point and change its chemical composition”
In the official news release, [researchers (see below)] have found that laser pulses are able to snap the electronic interactions in a compound containing copper, oxygen, and bismuth. The result is a condition when electrons do not repel each other. Moreover, this condition does not require a very low temperature, thus creating a superconductivity (sic) at room temperature.
Italy’s International School for Advanced Studies (SISSA) in Trieste, Università Cattolica di Brescia and Politecnico di Milano used suitably tailored laser pulses to snap the electronic interactions in a compound containing copper, oxygen and bismuth. They were thus able to identify the condition for which the electrons do not repel each other, that is an essential prerequisite for current to flow without resistance.
As described by the Brookhaven team, if you could engineer a superconductor that can operate at room temperature, you’re golden:
Picture power grids that never lose energy, more affordable mag-lev train systems, cheaper medical imaging machines like MRI scanners, and smaller yet powerful supercomputers.
Oh, yeah, you can milk anything with nipples.
The answer to this question [why superconductivity occurs under a variety of circumstances] holds major opportunities for scientific and technological development. About six percent of all electricity distributed in the U.S. is lost in transmission and distribution. Because superconductors don't lose current as they conduct electricity, they could enable ultra-efficient power grids and incredibly fast computer chips. Winding them into coils produces magnetic fields that could be used for highly-efficient generators and high-speed magnetic levitation trains.
By precisely measuring the entropy of a cerium copper gold alloy with baffling electronic properties cooled to nearly absolute zero, physicists in Germany and the United States have gleaned new evidence about the possible causes of high-temperature superconductivity and similar phenomena.
By studying this composition and measuring the entropy numerous times under varying conditions of stress, the Karlsruhe team was able to create a 3-D map that showed how entropy at very low yet finite temperature steadily increased as the system approached the quantum critical point.
No direct measure of entropy exists, but the ratio of entropy changes to stress is directly proportional to another ratio that can be measured: the amount the sample expands or contracts due to changes in temperature. To enable the measurements at the extraordinarily low temperatures required, the Karlsruhe team developed a method for accurately measuring length changes of less than one tenth of a trillionth of a meter—approximately one-thousandth the radius of a single atom.
It is quite remarkable that the entropy landscape can connect so well with the detailed profile of the quantum critical fluctuations determined from microscopic experiments such as inelastic neutron scattering, all the more so when both end up providing direct evidence to support the theory," he said
More generally, the demonstration of the pronounced entropy enhancement at a quantum critical point in a multidimensional parameter space raises new insights into the way electron-electron interactions give rise to high-temperature superconductivity, Si said. [???]
"One way to relieve the accumulated entropy of a quantum critical point is for the electrons in the system to reorganize themselves into novel phases," he said. "Among the possible phases that ensue is unconventional superconductivity, in which the electrons pair up and form a coherent macroscopic quantum state."
Scientists at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have combined two microscopy techniques to peer into the interactions that occur between electrons and the atomic vibrations of a material. They found that the coupling between electrons and atomic vibrations is ten times stronger than anyone had previously believed.
This new insight could lead to superconductivity at much higher temperatures than previously thought possible, leading to a large ripple effect on applications including improved energy transmission in cables and faster electronics and communication.
In research described in the journal Science, the scientists combined an X-ray free-electron laser together with a technique called angle-resolved photoemission spectroscopy (ARPES) to image the atomic vibrations of a material and to see how those vibrations affect the electrons in the same material.
In a 2014 paper published in Nature, Shen and his colleagues sorted out what was causing the effect. It turns out that the atomic vibrations [phonons] in the STO [strontium, titanium, oxygen] travel up into the iron selenide and give electrons the additional energy they need to pair up and carry electricity with zero loss at higher temperatures than they would on their own.
“What this experiment has shown is that the fact previous simple theory of electron-phonon interaction cannot explain the superconductivity in this compound does not mean that we need to throw out the phonon,” said Shen “It could be that all players are active, and we need to look at the problem in a more holistic way.”