Prerequisite for Room Temperature Superconductor Found

What they found was odd - as the material warmed up from absolute zero, the amount that a magnetic field could penetrate the material increased linearly instead of exponentially, which is what is normally seen with superconductors.

After running a series of measurements and calculations, the researched concluded that the best explanation for what was going on was that the electrons must have been disguised as particles with higher spin - something that wasn't even considered as a possibility for a superconductor before.

While this new type of superconductivity still requires incredibly cold temperatures for now, the discovery gives the entire field a whole new direction.

"We used to be confined to pairing with spin one-half particles," says lead author Hyunsoo Kim.

"But if we start considering higher spin, then the landscape of this superconducting research expands and just gets more interesting."

This is incredibly early days, and there's still a lot we have to learn about exactly what's going on here.

But the fact that we have a brand new type of superconductivity to test and measure, adding a cool new breakthrough to the 100 years of this type of research, is pretty exciting.

sciencealert.com - Physicists Just Discovered an Entirely New Type of Superconductivity.

Full disclosure: This was not found at some high temperature and it was also under pressure.

The OP explains Cooper pairs. Those are pairs of electrons with 1/2 spin. This announcement is about finding superconductivity in 3/2 spin electrons. Everybody expected it to be there but in something like a gas for not a solid material. This discovery abuts against the next news item.

By applying an algorithm to a strange section of the periodic table of elements, physicists have at last been able to predict which elements could pair up with hydrogen to create a room temperature superconductor - one of the "holy grails" of physics.

Now, researchers from the Moscow Institute of Physics and Technology and Skoltech, Russia, have devised a process to pick out which of a special type of metals, known as actinides, in the periodic table would be stable enough under certain conditions to exhibit superconductivity.

And it's already led to the discovery of a material that could become a superconductor at a relatively toasty minus 20°C (minus 4°F) - although it still needs to be squeezed under high pressure.

The actinides are a series of 15 metals with large atomic numbers 89 to 103 (actinium to lawrencium), sitting alongside that other weird 'outside' block of elements, the lanthanides.

Observations of the way various metal hydrides conduct electricity at certain temperatures had led researchers to suspect there was a pattern reflected by their positions in the periodic table, but the exact link wasn't clear.

This new algorithm used the arrangements of the electrons in the actinide series of elements to predict which could team with hydrogen to provide an ideal lattice, one that would result in a strong electron-phonon interaction.

The result is the discovery of superconducting actinium hydrides that could be as warm as minus 20°C (minus 4°F).

They still need 1.5 million atmospheres of pressure, but having a better handle on how to pick and match elements to create 'warm' superconducting materials is a find worth paying attention to.

While there are still plenty of hurdles to overcome before we can expect to have resistance-free technology in our home, discovering a general principle linking the phenomenon with the periodic arrangement of elements is a significant step forward.

And it's already led to the discovery of a material that could become a superconductor at a relatively toasty minus 20°C (minus 4°F) - although it still needs to be squeezed under high pressure.

sciencealert.com, April 12, 2018 - A Pattern Hidden in The Periodic Table Could Lead to The Holy Grail of Superconductors.

Most of the research is centered around cuprates (i.e., containing copper) that are ceramic in nature. Looking at other atoms was not very interesting because a lot of materials are super conducting.

This is like finding a spice market when you only had salt and sugar!

Add the two stories together... you can kind of see what should happen next: a new recipe at normal atmospheric pressure and at dry ice temperatures!

This is going to take some explaining.

SC - Super Conductor. A material that looses all resistance allowing electricity to flow through.

HTSC - High Temperature Super Conductor. Instead of being close to absolute zero these materials become SC at warmer temperatures.

Critical Temperature - Transition point in a material when it becomes a SC.

BEC - Bose-Einstein Condensate. A material made by lowering the temperature so all the molecules making up the BEC behave as one atom sharing the same quantum state. Good example is liquid helium that climbs out of its container. That is a jar of helium gas super cooled down to a BEC.

Cooper Pairs - Electrons that pair up and thought to be the cause of super conductivity. AKA, BCS Pair.

BCS Theory of SC - Named after John Bardeen, Leon Cooper, and John Robert Schrieffer, who theorized that interaction of electrons in the crystal lattice structure of SC materials create Cooper Pairs.

Polaron - A "quasi-particle" used to describe electron interaction in the crystal lattice SC. The crystal lattice deforms but does not break and electrons travel through the lattice in waves.

Bipolaron - A pair of polarons bound by a phonon.

Armed with a few terms what follows should make some sense. This researcher was measuring various aspects of BEC. This is theoretical (the calculations were done with an idealized BEC) but what it explains is what BCS Theory cannot. And that is what is important (not all the geeky terms which are my own explanations to myself, they are just "high-level" and not scientific, spot-on, writing a paper bound for the arxiv level). To the news...

Victor Lakhno, head of the Laboratory of Quantum-Mechanical Systems of the Institute of Mathematical Problems of Biology, RAS -- the Branch of Keldysh Institute of Applied Mathematics RAS has calculated a critical temperature of the transition, energy, heat capacity and heat of transition of an ideal three-dimensional Bose-condensate of translation-invariant bipolarons (TI-bipolarons). The results obtained offer an explanation of the experiments with high-temperature superconductors.
...

In his calculations he proceeded from the same factors as the classical BCS theory did. However He excluded the electron variables from the Froehlich Hamiltonian of electron-phonon interaction instead of the phonon ones. Since in the case of a linear dispersion law (as in the BCS) phonons represent quantized acoustic waves, it can be said that in the TI-bipolaron theory, SC is caused by charged acoustic waves which form a SC condensate. In the case of HTSC materials, according to his theory, we deal not with acoustic phonons, but with optic ones since these materials are ionic crystals. As a result, the theory describes a charged Bose gas of optical phonons coupled with electron pairs which are translation-invariant (TI) bipolarons. Like Cooper pairs TI-bipolarons are plane waves possesing a small correlation length equal to several constants of the crystal lattice.

The qualitative difference of this theory from the other ones is that it implies that even at zero temperature only a small portion of all the electrons are in the TI-bipolaron (paired) state. This corresponds to the results obtained in Bo�ovi? [sic] et al experiments in 2016 and opens up new opportunities for creation of room-temperature superconductors. Since this theory suggests that in order to enhance the critical temperature of the transition, one should enhance the concentration of TI-bipolarons.

Eurekalert.org, May 24, 2018 - Theory gives free rein to superconductivity at room temperature.

What has been found is an explanation of one material (BEC) that gives rise to similar properties in another material (HTSC) and a method of inducing that property (i.e., Cooper pairs), even at room temperature!

To produce a superconducting cable operable at room temperature one should use strongly underdoped HTSC material (whose SC transition temperature is very low, i.e. a few K). This material, however, already contains bipolarons, though in very small quantity. It only remains to enhance their concentration without resort to doping. This can be arranged by making the cable coaxial so that the internal small-diameter cable isolated from the external one could induce a strong electric field attracting bipolarons.

Victor Lakhno (same source)

There you go ATS! A room temperature superconducting cable for lossless energy transmission.

I said to get nuclear fusion up and going we first need energy storage and efficient energy transmission. Vanadium redox flow batteries have had the national regulations clarified (USA) so that is about to happen nationwide. A theoretical loss-less Room Temperature SC seals the deal.

Can we get on with our nuclear fusion future??

For comparison, room temperature in Kelvin is 293 - 298.

BCS Theory stated SC could not go above 30 K. When HTSC were discovered that proved to not be true (160 K). Hydrogen sulfide has been demonstrated as SC at 203 K but under high pressure.

Fun read at singularityhub.com - Why the Discovery of Room-Temperature Superconductors Would Unleash Amazing Technologies.

FYI, Wikipedia: Coaxial Cable.

a reply to: TEOT

Now, to see how well everybody is paying attention!

The superconducting material, LaH10, is the latest pressurized hydride to exhibit high Tc through conventional superconductivity, the kind described by the six-decade-old Bardeen-Cooper-Schrieffer (BCS) theory. The revival of interest in BCS superconductivity stems from work by Neil Ashcroft, who predicted a half-century ago that hydrogen would not only become metallic under pressure but would also be a high-temperature superconductor. In 2004 the Cornell University theorist proposed a more practical means of realizing those properties: Rather than crush pure hydrogen to unleash its metallic abilities, subjecting a hydrogen-rich compound to lesser compression might yield similar results. Chemical bonding would do some of the work in forcing hydrogen atoms together and inducing the coupling of electrons and lattice vibrations, or phonons, that hastens BCS superconductivity.

The researchers crushed La and H2 between diamond anvils at room temperature and then laser heated the concoction. X-ray diffraction measurements revealed a distinct shift in structure at about 1000 K and 170 GPa. As predicted, LaH10 emerged with a caged structure of 32 H atoms surrounding each La atom, Hemley’s team reported in Angewandte Chemie last November. The resulting configuration pushed adjacent H atoms to within 1.1 Å of each other, a distance that’s consistent with predictions for metallic hydrogen and thus seemingly ideal for realizing high-temperature superconductivity.

The final step was to measure the electrical properties. Over the past several months, Hemley and colleagues performed several trials in labs at George Washington, the Carnegie Institution for Science, and Argonne National Laboratory. Using a four-point probe on a 5-μm-thick sample pressurized to 190 GPa, they measured a sudden drop in resistance, to about 0.5 μΩ, at 260 K. Analysis of three other samples with a less precise technique yielded evidence of sudden drops in resistance at temperatures as high as 280 K at 200 GPa. A pressurized sample of pure lanthanum showed no such resistance change.

The day after receiving a summary and figures of Hemley’s forthcoming paper, Eremets, who once worked for Hemley as a research scientist, submitted a paper of his own to arXiv. He and his team report a Tc of 215 K in a sample of lanthanum and hydrogen pressurized to 150 GPa.

Neither Hemley’s nor Eremets’s teams tested for the Meissner effect, though both plan to.

Physics Today (physicstoday.scitation.org), Aug. 23, 2018 - Pressurized superconductors approach room-temperature realm.

Well, if you recall, researchers at the Max Planck Institute did get superconducting in a sample at room temperature and regular atmosphere which promptly disintegrated. And the other thing to recall is Harvard saying they created metallic hydrogen and were ready to ship their sample to Argonne Labs when their diamond anvil imploded. Metallic hydrogen is supposed to be a room temperature, meta-stable, superconductor.

What these guys did is what was suggested, they took hydrogen and lanthanum mixture, crushed that together, heated it up with a laser (the answer is always: frikken' lasers!), that created a special alignment, thus realizing what was speculated in theory.

150 - 200 Giga Pascals is a lot of pressure! But the intent was to show how alignment of hydrogen in an analog of its metallic state would show the same properties of pure metallic hydrogen.

This offers clues on where to look next and try making higher Tc superconductors.

originally posted by: Arnie123
a reply to: TEOTWAWKIAIFF

You could technically milk a hamster, creamer much?

Post of the day! ROTFLMFAO!

As a sample material, we decided to use the slightly overdoped bi-layer cuprate (Pb,Bi)2Sr2CaCu2O8+δ with Tc = 79 K. The substitution of Pb for Bi has the advantage of supressing the characteristic supermodulation seen in many Bi-based cuprates, simplifying the interpretation and making higher-voltage measurements possible.

nature.com - Charge trapping and super-Poissonian noise centres in a cuprate superconductor.

A material can either be insulating or conductive. In an insulator, an extra electron will get trapped. Thus, no electric current flows in insulators. In a conductor, extra electrons will immediately flow. The more conductive the material is, the faster the electrons will flow.

The research group of Leiden physicist Milan Allan was therefore surprised to discover charge trapping in a material with zero resistance. Charge trapping is supposed to be a telltale sign of an insulator. Together with Leiden theoretical physicist Jan Zaanen, Allan's group found that the phenomenon could unravel a longstanding mystery about charge transport in a family of materials called cuprates. These poorly understood materials have no resistance, even at relatively high temperatures, and are therefore labeled high-temperature superconductors. The mechanism behind those is one of the big mysteries in physics today.

phys.org, Oct. 8, 2018 - A mysterious insulating phenomenon in a superconductor.

Again, a little editorial privilege for me! phys.org did a poor job explaining and showing science in their article.

Cuprates are copper ceramics and the whole of superconductivity research got a kick in the neck when, against all known science at the time saying, "That is it! We can only have superconductivity up to these temperatures and no more!", the first high temperature superconductor (HTS) were shown and demonstrated (found in 1970s in non-elemental materials and researched in the 1980s, with a big news in 86. Cuprates are still being researched as to "why" HTS happens).

What phys.org did was to not show you (or me) what was being researched, how it varied from other research, and what temperature they were at! They subbed out bismuth with lead to keep electron fluctuation from happening as much along the axis of SC. That allowed them, with a scanning tunnel microscope (they built it by hand over a 2 year period! It measures atomic level noise!), to add "noise filters" at certain junctions and measure across the spectrum of carrier current what was happening.

Even after cooling down to the Tc where resistance disappears they found small islands of trapped charges! As the article points out, that is what an insulator does! But they did not explain it very well! From the Nature article,

Two tunnelling processes are present, one fast, accounting for almost all the tunnelling current, and one slow, acting as a switch for the first process. This switching mechanism is usually based on Coulomb interaction. For example, if the state of the slow process is occupied, it raises the energy level of the state necessary for the fast process and effectively blocks it...

So what? Right? It means, that any impurities or non-uniform crystal junctions can be engineered out. Higher density of SC material usually means increase in amount of load current. And could also be the way forward in raising the critical temperature even higher! Maybe even add in a "control" for the Coulomb switch or at least dampen it down so it no longer interferes as much as they currently do.

New Record Set

The work comes from the lab of Mikhail Eremets and colleagues at the Max Planck Institute for Chemistry in Mainz, Germany. Eremets and his colleagues say they have observed lanthanum hydride (LaH10) superconducting at the sweltering temperature of 250 K, or –23 °C.

That’s warmer than the current temperature at the North Pole. “Our study makes a leap forward on the road to the room-temperature superconductivity,” say the team. (The caveat is that the sample has to be under huge pressure: 170 gigapascals, or about half the pressure at the center of the Earth.)

technologyreviewe.com, Dec. 10, 2018 - The record for high-temperature superconductivity has been smashed again.

That is crazy! Even warmer than dry ice!! They have it a incredible pressure but that is OK. It is the ability to mess around with the formulation and getting closer to room temperature that is impressive! Without metallic hydrogen around we may see Tc hit the room temp mark (at huge, crazy pressure!).



Wow!