Superconductors -- Powering Our Future
(Inside Science) -- A maglev train hovers above its track. A doctor uses an MRI scanner to detect disease. Fast digital circuits send superfast, clear signals from one source to another. These technologies are possible thanks to superconductors. Superconductors are materials where electrons can move without any resistance. But today's superconductors don’t work unless they are cooled to well below room temperature. Now researchers are using quantum physics on a quest to find superconductors that will work at room temperature to make them easier to use. There’s been a problem in physics that researchers are trying to solve for years: Can we find something that can superconduct at room temperature? If we find it, it will revolutionize how we transport and use energy. “If you had a room temperature superconductor in your pocket, you then hope there would be some very interesting applications that would come out of this,” said Richard Greene, physics professor at the University of Maryland.
When lead, mercury and certain compounds are cooled to extremely cold temperatures, they become superconductors. They stop showing any electrical resistance and they expel their magnetic fields, which makes them ideal for conducting electricity. But you need to use liquid helium if you’re trying to get down to absolute zero (-459 degrees Fahrenheit). That’s why physicists want to find a high temperature superconductor that will work at room temperature -- it’s just down right easier to work with. Researchers discovered superconductivity in 1911. By the ’60s, they thought they had solved all of its mysteries. But in 1986 two scientists in Zurich discovered superconductors that work at higher temperatures than researchers thought were ever possible. “So this set off a gold rush of activity, because we were really surprised that this could happen. It occurred also in oxide materials, which was totally unexpected, and these were materials that were not very conducting at all,” said Greene.
These materials work as high temperature superconductors up to -225 degrees Fahrenheit. Now that we have materials that can superconduct above the boiling point of nitrogen, we can finally use them in certain applications. Neither MRI machines or the particle accelerator at CERN would have been possible without the use of liquid helium-cooled superconducting electromagnets.
“Superconductivity is what I would call an emergent property of materials. It’s not something you can predict by knowing how a few atoms work or a few electrons work. You really need to understand how many atoms and electrons together produce properties, and this of course requires knowing quantum mechanics, which was only invented in the 1920s,” said Greene. Researchers still do not understand how to predict which material will be a high temperature superconductors or what causes their superconductivity. “These new superconductors have many strange properties that are not understood even today. They do not go, they just don’t follow the normal paradigm that we are used to for conventional metals,” said Greene.
Greene is studying copper oxide and iron-based superconductors for clues on why the electrons inside them act in such an unconventional way. Solving the problems that come with higher temperature superconductors -- Greene believes researchers will discover a room temperature super conductor in the next 30 years. If that happens, it could solve one of the greatest mysteries of physics -- at the tiniest level.