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New Superconductor Theory May Revolutionize Electrical Engineering
An anonymous reader writes "High-temperature superconductors exhibit a frustratingly varied catalog of odd behavior, such as electrons that arrange themselves into stripes or refuse to arrange themselves symmetrically around atoms. Now two physicists propose that such behaviors – and superconductivity itself – can all be traced to a single starting point, and they explain why there are so many variations. Most subatomic particles have a tiny magnetic field – a property physicists call 'spin' – and electrical resistance happens when the fields of electrons carrying current interact with those of surrounding atoms. Two electrons can join like two bar magnets, the north pole of one clamping to the south pole of the other, and this 'Cooper pair' is magnetically neutral and can move without resistance. Lee and Davis propose that this 'antiferromagnetic' interaction is the universal cause not only for superconductivity but also for all the observed intertwined ordering. They show how their 'unified' theory can predict the phenomena observed in copper-based, iron-based and so-called 'heavy fermion' materials."
I will go on the record as saying I am 100% in favor of superconductors. All you anti-supercondites can chomp it!
to one of the BASIC test programs for my Commodore 64 that would fill the screen with random / and \ characters, resulting in a similar pattern. If only I'd made the connection to intertwined ordered phases earlier!
Mostly random stuff.
Would it kill them to link to the original paper? It's not even paywalled:
http://www.pnas.org/content/110/44/17623.full.pdf+html?sid=5925a7b2-3efe-4a21-99f9-0e448cd3a7cf
And calling an electron's spin angular momentum is like calling earth's angular momentum temperature.
If you keep your room at 2 Kelvin, sure.
Now there was a superconductor. Odd behaviour and all.
FWIW, this appears to be mostly first order theory that is able to exhibit the known interactions that are presumed to destabilize known forms of high-temp superconductivity. It isn't a revolutionary idea, many physicists presume that the interaction of the topology of the Fermi-surface are keys to understanding why some high-temp superconductors work and some do not, but I'm guessing these folks are one the first to show a way to generate most of the known interactions in most types of known high-temp superconductors (apparently other people have done this for copper-oxide HTSC) and hence why this is considered a "unified" theory.
The insight they appear to claim is there aren't certain configurations of Fermi-surfaces that generate interactions that destabilize HTSCs, but the key is in the energy regime of electron-electron interaction of the anti-ferromagnetic interaction itself. It's kind of like saying in the domain of the formation of these superconductivity inhibitors, it's too simplifying to consider energy regime of particle-field interaction (e.g., electron-pair vs Fermi-surface) but you must consider the energy regime of particle-particle interaction.
Like all things new, it may be a start, but on the other hand, it is still an untested theory (it's a theory crafted to exhibit known results). If it turns out to be predictive, maybe it might lead to something interesting.
"Ideally we would like to be able to tell the materials scientist to put elements X, Y and Z together," Lee said. "Unfortunately we can't do that yet."
You can't fool me, young man-- it's fields ALL the way down!
Oh, boy! Superconductivity at 53 C, according to a website run by some guy whose only verified achievement is landing the "superconductors.org" domain. Stop the presses!
For the sarcasm-impaired: If someone had, in fact, produced a material that verifiably and reproducibly exhibits superconductivity at such temperatures, it probably would be getting some coverage outside a single vanity domain.
(Why was a poorly written press release linked instead of the actual paper?)
This paper shows how you can start with an extremely simple theory of electron interaction and build up to some very complicated, realistic superconducting behaviors. When varying the material properties of high temperature superconductors, you always see an antiferromagnetic material type near the superconducting material composition. For many years condensed matter physicists have suspected that this was more than a coincidence and that high temperature superconductors work because of finely tuned antiferromagnetic interactions between electrons. Although this paper simplifies electron interactions considerably (come on, we're physicists, simplification is what we do), it does fill in some of the larger holes in that theory and is an important step toward understanding the physics behind the phenomenological high temperature superconductivity models.
You do not need 2K for supraconduction: there is at least one class of supraconductor ceramics that works at temperatures as high as 135K and another (YBCO) that works at 92K which makes them relatively simple to cool by simply using liquid nitrogen. Most of the others operate in the 25-55K range.
Too bad China has the monopoly on rare earths.
They're not actually rare. China has a monopoly mainly by being a very cheap producer of something that requires a lot of messy processing to make; everyone else is happy to let them have a monopoly because it's expensive to do otherwise, not because they actually control all possible sources.
"Little does he know, but there is no 'I' in 'Idiot'!"