I know the people involved, though I haven't run my interpretation past them, so here goes:
They fit data, using a "genetic algorithm", to 2 different models of the superconductor. They find that the magnetic model works better. (Don't ask me how much better)
Relevance: high temp superconductors are believed to work through magnetic interactions. So this is compelling evidence of that. However, the models here are fairly simple ones, not sophisticated ones you would use if you were a hardcore numerical physicist
I would say that they are trying to put the spotlight on the experimental technique, OTOH
Usually you can read the peer review file usually they are not paywalled and more illuminating than the abstract but I guess nature physics is not into that business
Waiting for a resident expert to show up and explain if the press release is correct and this is actually a big deal, solving a 30-year-old puzzle and all.
I'm not an expert, but as I understand it there isn't a complete theory about why high-temperature superconductors work, so inventing new HTS types is sort of a matter of just trying different materials and hoping you get lucky. If this new research fills in some important gaps then it might make it much easier to discover better materials.
These would have some practical applications. Cheaper MRI machines. Long-distance lossless power transmission. Tokomak-style nuclear fusion reactors use superconductors to maintain magnetic confinement, so better HTS materials mean better magnets, which means a more efficient reactor that doesn't have to be quite so big. (The MIT Sparc reactor design uses ReBCO tape.)
As is unfortunately usual with press releases, this press release is gobbledygook that doesn't really give any useful information about what is going on. The word "vanish" in particular is very poorly chosen: it does not appear at all in the actual paper, and of course the actual paper nowhere claims that electrons just vanish (which is physically impossible--the only way to make an electron "vanish" is to annihilate it with a positron, and nothing of that sort is going on here).
What is actually happening, as far as I can gather (I am not an expert in this field and the paper is pretty technical, obviously written for other experts and not for a more general audience), is that at the superconducting transition, the shape of the Fermi surface changes, and this has the effect that ways for interactions to occur inside the material that were available above the transition temperature (which is roughly what the term "quasiparticles" means) become forbidden below the transition temperature. This transition into formerly allowed interactions becoming forbidden is what allows the material to be superconducting below the transition temperature: basically, the now-forbidden interactions were the ones that were causing nonzero electrical resistance inside the material by dissipating energy. This could very roughly be described as quasiparticle modes "vanishing", but to call that "electrons vanishing", as the press release does, is, as I said above, a very poor choice of terminology.
Interesting. Before reading the abstract and press release, I assumed "vanish" was PR-speak for "join into Cooper pairs". It sounds like it's something else, though. A "Fermi Surface" seems to be defined in terms of a bunch of other things I have no idea about, so unless someone comes along with a really good ELI5 I don't think I'm going to get it...
> I assumed "vanish" was PR-speak for "join into Cooper pairs".
I don't think so, because that is a known and well-understood feature of any superconductor (not just high temperature), and the press release makes it seem like whatever this "electron vanishing" thing is, it's something just discovered in this paper, or at least something that's particular to the high temperature superconductors being studied in this paper.
> A "Fermi Surface" seems to be defined in terms of a bunch of other things I have no idea about
Electrons are fermions, which means they obey the Pauli exclusion principle. So if you imagine a piece of material like this "cuprate" semiconductor and start out with zero electrons anywhere in it, and then you start to put electrons in, no two electrons can be in the same state so they will start filling energy levels from the lowest level on up, in much the same way as electrons fill energy levels in a single atom. So you can, very roughly, think of the material as being "filled" with electrons the way a container fills with a fluid. The "Fermi surface" is then just the "surface" of the electron "fluid" filling the material, when the material has its usual number of electrons based on how many atoms are in it and what type of atoms they are. In less metaphorical language, it is the "surface" formed by the highest energy levels that are filled.
In a single atom, the energy levels are pretty much fixed regardless of external variables like temperature (external electric or magnetic fields can change them some, but not a lot, and not in ways that change the qualitative behavior of the atom). But in a material containing a very large number of atoms (there will be something like 10^23 of them in a typical sample of superconductor material like those in this experiment), the energy levels can change as temperature and other external variables (like the magnetic field) change, not just by small shifts, but by changing the whole "shape" of the levels, and hence of the Fermi surface. That appears to be what is happening in these superconductors.
Turns out it's not a super esoteric concept. It is a "map of where the electrons are", but (and of course the uni PR won't tell you this) it's not a literal position map, it's a map in momentum space. And like you say, it's focused on the highest energy electrons. So it's really saying how the highest energy electrons are distributed in momentum space.
I read that page before posting. It's pretty dense. :) Eventually I got to the "map in momentum space" part and it started making more sense, but I still had to read the page about energy bands a couple times, and it's still pretty hazy.
This appears to be a university press release and I'm rather disappointed it didn't include the traditional absurd claims as to why this vitally important to the future of humanity ("superconducting cables could increase the speed by which consumer video could be streamed from the cloud", or maybe "Scientists believe spacecraft made of superconductors could be electronically launched from earth orbit to nearby stars").
In reality, if this effect is real it is important, basic science.
They fit data, using a "genetic algorithm", to 2 different models of the superconductor. They find that the magnetic model works better. (Don't ask me how much better)
Relevance: high temp superconductors are believed to work through magnetic interactions. So this is compelling evidence of that. However, the models here are fairly simple ones, not sophisticated ones you would use if you were a hardcore numerical physicist
I would say that they are trying to put the spotlight on the experimental technique, OTOH
Usually you can read the peer review file usually they are not paywalled and more illuminating than the abstract but I guess nature physics is not into that business