New Superconductor Theory May Revolutionize Electrical Engineering 92
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."
Re:magnets (Score:1, Interesting)
Spin a magnetic field? (Score:2, Interesting)
Spin is an angular momentum, yes it does generates a magnetic momentum that gives origin to a field. But calling spin a field is like calling earth's angular momentum gravity.
my take... (Score:3, Interesting)
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."
Re: that picture takes me back (Score:4, Interesting)