'Electron pairing' found well above superconductor's critical temperature

phys.org ^ | 08/21/2019 | Jade Boyd, Rice University

[BenLurkin]

Physicists have known since 1911 that electricity can flow without resistance in materials called superconductors. And in 1957, they figured out why: Under specific conditions, including typically very cold temperatures, electrons join together in pairs—something that's normally forbidden due to their mutual repulsion—and as pairs, they can flow freely.

Electron pairs are named for Leon Cooper, the physicist who first described them. In addition to explaining classical superconductivity, physicists believe Cooper pairs bring about high-temperature superconductivity, an unconventional variant discovered in the 1980s. It was dubbed "high-temperature" because it occurs at temperatures that, although still very cold, are considerably higher those of classical superconductors. Physicists have long dreamed of making high-temperature superconductors that work at room temperature, a development that would radically change the way energy is made, moved and used worldwide.

But while physicists have a clear understanding of how and why electron pairing happens in classical superconductors, the same cannot be said of high-temperature superconductors like the lanthanum strontium copper oxide (LSCO) featured in the new study.

Every superconductor has a critical temperature at which electrical resistance disappears. Natelson said theories and studies of copper-oxide superconductors over that past 20 years have suggested that Cooper pairs form above this critical temperature and only become coherently mobile when the material is cooled to the critical temperature.

In the Nature study, Natelson and colleagues found evidence of this higher energy pairing in the conduction noise in ultrapure LCSO samples grown in the lab of Brookhaven's Ivan Božović, co-corresponding author of the study.

By measuring the variation in the discrete amount of electrical charge flowing through LCSO junctions, Natelson and colleagues found that passage of single electrons could not account for the amount of charge flowing through the junctions at temperatures and voltages well above the critical temperature where superconductivity occurred.

[Revel]

Because this is a bunch of talk that goes way above what most people can understand and then in the end there is admission that if may all amount to noting in the practical sense.

[Scram1]

At the U of A the researchers didn’t use ventilators with rat poison elements.

A problem with this technique is that the resulting compound must have the right ratio of atoms — in the case of the yttrium-barium-copper-oxide, the magic ratio is 1-2-3-4. Another problem is the toxicity of some elements. One superconducting compound broke all temperature records, but it contained the highly poisonous element thallium, used in rat-poisons. Some researchers were scared to try to make the compound, because of toxicity.

[dixjea]

Is this a step towards nuclear fusion (as opposed to fission)? If so that is really really cool.

[SunkenCiv]

Oh, it is, isn't it? I did that a couple of weeks ago, which is not that different to my shaky old remembery.

[SunkenCiv]

Fusion is unrelated (IMHO, I guess we'll all find out together) -- but if ambient temperature superconductivity can be achieved and practical, the effective generating capacity will roughly triple once the grid is replaced with the new material.

[Chode]

Lanthanum strontium copper oxide, but is it Gold-Pressed???

wait, never mind...

[Ozark Tom]

You may find interest in the publications of Professor Leif Holmlid of the University of Gothenberg. Unfortunately, his medical issues have limited further contributions toward an alternative form of laser initiated fusion of ultra-dense deuterium.

[_Jim]

I’ll look into his work, thanks.