Laser blasts could unlock secrets of practical superconductors

Illustration for article titled Laser blasts could unlock secrets of practical superconductors

Take an ordinary, non-superconducting material and hit it with light, and its electrons suddenly reorganize into a resistance-free, superconducting arrangement. This only works at extremely low temperatures, but it could help us solve the riddle of practical superconductors.


Oxford professor Andrea Cavalleri explains what they have managed here:

"We have used light to turn a normal insulator into a superconductor. That's already exciting in terms of what it tells us about this class of materials. But the question now is can we take a material to a much higher temperature and make it a superconductor?"

Superconductors are exactly what they sound like: they're perfect conductors of electric current, managing to carry the current with absolutely no resistance or energy loss. It's a field that science is still struggling to really understand, particularly why certain materials become superconductors under certain very specific conditions - always involving extremely low temperatures - and why other materials fail to make the leap.

Because superconductors only work at temperatures close to absolute zero, their practical uses are severely limited, even though their potential applications are enormous. This latest research hasn't solved that problem, but it's perhaps found a piece of the solution that will someday take us to practical superconductors. Researchers hit a non-superconducting material with light, and for a fraction of a second the atoms and electrons inside the material shifted into a perfect superconductor arrangement.

Now, this only worked at 20 degrees above absolute zero, and again this effect only lasted for an instant and then the material reverted back to its normal state. This isn't going to take us directly to a practical solution, but it does mean materials can suddenly turn into superconductors, perhaps if some opposing force holding them back is temporarily nullified by the light.

Professor Cavalleri explains:

"We have shown that the non-superconducting state and the superconducting one are not that different in these materials, in that it takes only a millionth of a millionth of a second to make the electrons "synch up" and superconduct. This must mean that they were essentially already synched in the non-superconductor, but something was preventing them from sliding around with zero resistance. The precisely tuned laser light removes the frustration, unlocking the superconductivity."


That's one theory - again, the science of superconductors is still very imprecise, even a hundred years after their initial discovery - but it offers the researchers a clear next step on a road that will hopefully lead to room temperature superconductors. Cavalleri offers this rather realistic assessment of what's next:

"There is a school of thought that it should be possible to achieve superconductivity at much higher temperatures, but that some competing type of order in the material gets in the way. We should be able to explore this idea and see if we can disrupt the competing order to reveal superconductivity at higher temperatures. It's certainly worth trying!"




Stephan Zielinski

Re: Because superconductors only work at temperatures close to absolute zero, their practical uses are severely limited, even though their potential applications are enormous.

There are plenty of superconductors that work way above absolute zero, and have been for over twenty years. Example: thallium barium calcium copper oxide is superconductive at 127K. (For comparison, liquid nitrogen is 77K. Water ice melts at 273.15K.)

However, such compounds remain very expensive and difficult to work into useful shapes. The quest for "high temperature superconductors" is, from an applications point of view, more a quest for cheap, easily worked high-temperature superconductors.

As you'd expect, more detail than you're likely to want is available at