Inducing Room-Temperature Superconductivity: New Opportunities Brought up by Research Using Light
Finding a breakthrough
Similar to how people discover more about themselves by moving beyond their comfort zones, scientists can discover more about a system by making it unstable and observing what occurs as it settles into a stable state.
When it comes to a superconducting material referred to as yttrium barium copper oxide or YBCO, experiments have revealed that under specific conditions, provoking instability with a laser pulse makes it possible for it to superconduct (conduct electrical current without any loss of energy) at closer to room temperature than scientists anticipated. This could be a big deal, considering that researchers have been chasing room-temperature superconductors for more than 30 years.
Is it viable?
However, do observations of this unstable state have any impact on how high-temperature superconductors would operate in real life, where applications like power lines, particle accelerators, maglev trains, and medical devices require them to be stable?
A study released by Science Advances suggests that the solution is yes.
Jun-Sik Lee, a staff researcher at the Department of Energy’s SLAC National Accelerator Laboratory and leader of the international research team that executed the research, stated that most people assumed that although this kind of research was helpful, it was not highly promising for future applications.
Jun-Sik Lee continues by adding that, however, now that the team has presented that the fundamental physics of these unstable states are quite comparable to those of stable ones. Opening up substantial possibilities, including the possibility that materials might additionally be pushed into a short-term superconducting state with light. It is an intriguing state that we can not see any other way.
The Name?
YBCO is a copper oxide compound, or cuprate, a member of a family of materials discovered in 1986 to conduct electric current with zero resistance at greater temperatures than researchers had believed possible.
Like traditional superconductors, which had been found more than 70 years earlier, YBCO switches from a typical to a superconducting state when cooled below a specific transition temperature. There, electrons pair up and create a condensate– a kind of electron soup– that effortlessly conducts electric current. Researchers have a strong theory of how this takes place in older superconductors. However, there is still no agreement concerning just how it works in unconventional ones like YBCO.
One way to tackle the problem is to examine the regular state of YBCO, which is plenty unusual in its own right. The typical state contains a number of complicated, interwoven stages of matter. Each with the potential to aid or impede the shift to superconductivity that jostle for dominance and occasionally overlap. What is more, in some of those stages, electrons seem to recognize each other and act together as if they were dragging each other around.
It is a genuine tangle, and scientists hope that understanding it better will clarify how and why these materials come to be superconducting at temperatures greater than the theoretical limitation anticipated for conventional superconductors. It is not easy to discover these remarkable normal states at the warm temperatures where they occur. Hence, researchers typically cool their YBCO samples to the point where they come to be superconducting. After that, they turn off the superconductivity restoring the typical state.
Changing is generally done by subjecting the material to a magnetic field. This is the preferred method because it leaves the material in a stable arrangement– needed to produce a practical device.
Lee stated that superconductivity could also be turned off with a pulse of light. This creates a standard state that’s slightly off-balance– out of equilibrium– where interesting things can occur from a scientific perspective. However, the instability has made researchers cautious of assuming that anything they discover there can also be applied to stable materials like those required for practical applications.
Static Waves
In this research, Lee and his partners compared both switching methods– magnetic fields and light pulses– by concentrating on how they influence a peculiar phase of matter referred to as charge density waves or CDWs, that show up in superconducting materials. CDWs are wavelike patterns of greater and reduced electron density. However, unlike ocean waves, they do not move.
Two-dimensional CDWs were discovered in 2012, and in 2015 Lee and his partners uncovered a new 3D type of CDW. Both types are totally linked with high-temperature superconductivity, and they can function as markers of the transition point where superconductivity switches on or off.
The research group did experiments at three X-ray light sources to compare what CDWs look like in YBCO when their superconductivity is turned off with light versus magnetism.
Initially, they measured the properties of the uninterrupted material, including its charge density waves, at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL).
After that, samples of the material were exposed to high magnetic fields at the SACLA synchrotron center in Japan and to laser light at the Pohang Accelerator Lab’s X-ray free-electron laser (PAL-XFEL) in Korea. This ensured that shifts in their CDWs could be measured.
SLAC staff researcher and study co-author Sanghoon Song stated that the experiments revealed that exposing the samples to magnetism or light produced comparable 3D patterns of CDWs. Although just how and why this occurs is still not understood. Sanghoon mentioned, the outcomes show that the states generated by either technique have the same fundamental physics. The team propose that laser light could be a good way to create and discover transient states that could be stabilized for functional applications– including room-temperature superconductivity.
Read the original article on PHYS.
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