Researchers at Brookhaven National Laboratory have discovered what makes a special class of material superconductive at relatively high temperatures, which might lead to a major breakthrough in electronics that allows superconductors to be used at room temperature.
The team of scientists, led by Ivan Božović, discovered that the key to superconductivity depends on the density of electrons pairing up.
Usually, this happens at very low temperatures (close to absolute zero), but in a special class of material known as cuprates, it happens at significantly higher temperatures, although still below freezing.
Cuprates are usually made of layers of copper oxide mixed with other elements such as strontium. Bozovic’s team spent 10 years analyzing 2,000 different samples of cuprates, each with a different amount of strontium, to work out what allows them to be superconductive at higher temperatures.
Superconductivity only happens under a certain temperature, and the team discovered that the temperature depends on the density of electron pairs, a state where electrons don’t repel each other anymore.
The electron pair state is a quantum mechanical effect that happens when the temperatures are low enough for electrons to stop repelling each other. Under those conditions, electricity flows with no resistance in the material and magnetic field lines are pushed outside.
In the study, which is published in Nature, they found that strontium helps the electrons pair up, making the superconducting transition temperature higher. Unfortunately, this only works up to a point. As the amount of strontium increases, it stops forming electron pairs and the material doesn’t possess its superconducting property anymore. The next step is to understand why exactly the electrons pair up.
"While in some sense we have answered the question why is the critical temperature so high in cuprate superconductors, other important questions are still open. The foremost ones are what causes strong local pairing and why are cuprates so exceptional in this respect. This is the focus of our research now," Božović told IFLScience.
Imagine electricity flowing from power plants to your home with no loss, electronic devices never heating, and fast silent trains crossing countries as fast as planes. This could be a not so distant future if we find a superconductor that works at room temperature.
"Room temperature superconductors have yet to be discovered, and this can only be done experimentally. However, if we have the correct theoretical picture, then instead of looking in every corner, we can focus the search in the right direction, thus increasing the chances significantly," Božović added.
Nevertheless, these wondrous materials are already employed. For example, CERN uses tens of kilometers of superconducting electrical cables in the Large Hadron Collider (LHC). The day of a room-temperature superconductor is not quite on the horizon yet, but we are a lot closer thanks to this research.