Superconductors news and discussions

[Powers]

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[spryfusion]

A superconductor claim blew up online. Science has punctured it.

Physics graduate student Hope Whitelock popped her head out of the lab at the University of Colorado Boulder on a recent morning to ask a bunch of scientists standing in the hallway for a quick gut check: “Can someone tell me if something is crazy?”

It’s been a few weeks of craziness for physicists and chemists scrambling to make sense of a grandiose claim that popped up in late July: the purported discovery by a team in South Korea of a material that conducts electricity at normal room temperature and air pressure — without losing any energy. The possibility of this long-sought material, called a room-temperature superconductor, quickly went viral, fueled by a video showing a lump of the stuff partially levitating as evidence of its extraordinary properties.

Now the claim is rapidly deflating under scientific study. Over the last few days, papers from academic labs scattered across the globe have built up evidence that LK-99 is not a superconductor and is more likely a type of magnet. (Hyun-Tak Kim, a co-author of one of the discovery papers and a physicist at William & Mary, countered in an email that other research groups’ failure to replicate their results are probably because they lack “know how” in developing the sample the same way.)

The episode has provided the public with an unusual front-row glimpse at a fundamental part of how science works.

Almost as soon as the initial paper appeared online, enthusiasts amplified the excitement among nonexperts, explaining the profound implications if this material, dubbed LK-99, is the real deal: a revolution for the power grid, more powerful medical imaging technologies, magnetically levitating trains — nothing short of a new era for humanity, and a slam dunk Nobel Prize to boot.

Suddenly, people who had never before heard of a superconductor considered the potential ripple effects of the technology. Careful experiments and abstruse calculations in academic labs were catapulted into mainstream interest; Whitelock says high school friends got in touch with her to ask what she thought. Other groups live-streamed their DIY attempts to re-create the material. Some onlookers put money on it, predicting whether it would pan out in volatile online betting markets.

The frenzy over LK-99 meant that scientific thinking evolved on an almost hourly basis, as new findings and videos of varying quality were shared, often via social media.

Philip W. Phillips, a condensed matter theoretical physicist at the University of Illinois at Urbana-Champaign was intrigued by the finding late last week, despite his doubts and questions about the initial papers.

“You don’t want to miss out on what could be the next big thing. That really drives physicists. It drives us all,” Phillips said on Friday.

By Tuesday night, though, the case was closed for him, based on a series of papers that came online in the last day making a convincing case that LK-99 is not a superconductor. “One more nail in the coffin,” Phillips wrote in an email, forwarding yet another paper that adds to the pile of evidence. “So your headline is quite simple.”

Read more here: https://www.washingtonpost.com/science/ ... -evidence/

Archive: https://archive.ph/GyMeG

[wjfox]

[firestar464]

rocks basically

[Powers]

rocks basically

Weird ones.

[firestar464]

Another of Ranga Dias's papers retracted

https://www.nature.com/articles/d41586-023-03398-4

[weatheriscool]

Research achieves photo-induced superconductivity on a chip
https://phys.org/news/2023-11-photo-ind ... -chip.html
by Jenny Witt, Max Planck Society

Researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, Germany, have shown that a previously demonstrated ability to turn on superconductivity with a laser beam can be integrated on a chip, opening up a route toward opto-electronic applications.

Their work, now published in Nature Communications, also shows that the electrical response of photo-excited K3C60 is not linear, that is, the resistance of the sample depends on the applied current. This is a key feature of superconductivity, validates some of the previous observations and provides new information and perspectives on the physics of K3C60 thin films.

The optical manipulation of materials to produce superconductivity at high temperatures is a key research focus of the MPSD. So far, this strategy has proven successful in several quantum materials, including cuprates, k-(ET)2-X and K3C60. Enhanced electrical coherence and vanishing resistance have been observed in previous studies on the optically driven states in these materials.

[weatheriscool]

A cause for 'strange' behavior of cuprates discovered, with superconductor ramifications
https://phys.org/news/2023-12-strange-b ... tions.html
by Polytechnic University of Milan

A recent study published in Nature Communications by researchers from Politecnico di Milano, Chalmers University of Technology in Göteborg and Sapienza University of Rome sheds light on one of the many mysteries of high-critical-temperature copper-based superconductors. Even at temperatures above the critical temperature, they are special, behaving like "strange" metals. This means that their electrical resistance changes with temperature differently than that of normal metals.

The research hints at the existence of a quantum critical point connected to the phase called "strange metal." A significant step forward in superconductivity research, the discovery could pave the way for sustainable technologies and contribute to a more environmentally friendly future.

[weatheriscool]

Field-induced superconductivity in quantum materials
https://phys.org/news/2023-12-field-ind ... rials.html
by Thamarasee Jeewandara , Phys.org

Field-induced superconductivity occurs when an applied magnetic field increases or induces superconductivity. In a new report published in Science Advances, Joshua J. Sanchez and a team of scientists applied stress as a switch between a field tunable superconducting state and a robust non-field tunable state, to mark the first demonstration of a strain-tunable, superconducting spin valve with infinite magnetoresistance.

The scientists combined tunable uniaxial stress and applied a magnetic field on the ferromagnetic superconductor to shift the field-induced zero resistance temperature. Using X-ray diffraction, and spectroscopy measurements under stress, the team proposed the origin of field-induced superconductivity to result from a new mechanism known as the dipolar fold.
Quantum materials in condensed matter physics

It is possible to switch between distinct electronic phases in quantum materials by tuning the parameters to show how they interact to drive technological development. An area of significant development includes ferromagnetism and superconductivity, whose antagonistic interactions lead to unusual phenomena including magnetic vortices, and spin-polarized supercurrents as promising methods for energy-efficient data storage.

Researchers have focused much attention on superconducting spin valves that surround a superconducting layer, for low energy dissipation information technologies. The development of such technologies can be limited by the very low temperatures required to implement them.

Aside from artificial heterostructures, a handful of single crystal materials showed field-induced superconductivity, melting doped-superconductors, and organic superconductors. In these materials and thin-film superconducting spin valves, the zero-resistance temperature is below 1 Kelvin, thereby limiting their practical applications.

[weatheriscool]

A new strategy for making and manipulating higher-temperature superconductors
https://phys.org/news/2023-12-strategy- ... ctors.html
by Harvard University

Superconductors have intrigued physicists for decades. But these materials, which allow the perfect, lossless flow of electrons, usually only exhibit this quantum-mechanical peculiarity at temperatures so low—a few degrees above absolute zero—as to render them impractical.

A research team led by Harvard Professor of Physics and Applied Physics Philip Kim has demonstrated a new strategy for making and manipulating a widely studied class of higher-temperature superconductors called cuprates, clearing a path to engineering new, unusual forms of superconductivity in previously unattainable materials.

Using a uniquely low-temperature device fabrication method, Kim and his team report in the journal Science a promising candidate for the world's first high-temperature, superconducting diode—essentially, a switch that makes current flow in one direction—made out of thin cuprate crystals.