By Joseph Wills
One of the most sought after results in modern applied physics is finding a room temperature superconductor. A conductor, of course, is a material that conducts electricity. A superconductor is a material that conducts electricity with no resistance, meaning (among some other characteristics) that no electricity is lost as it passes through the material. Superconductors are used in clinical settings such as medical equipment, hospitals or laboratories. The major hurdle to their widespread consumer adoption is the fact that most superconductors require temperatures far below zero: one of the “warmest” superconductors occurs at -70℃, at pressures several orders of magnitude greater than can be found in Earth’s atmosphere.
The quest for a room temperature conductor is the mission to completely revolutionize the way electricity is stored and distributed. A solar panel array in Arizona could power a house in upstate New York. Batteries could hold a charge ad infinitum. Technologies that rely on electromagnets -- including things like maglev trains, MRIs, and quantum computers -- would become almost unimaginably more powerful. Needless to say, a superconductor even remotely within acceptable human pressures and temperatures would change the world.
As reported in Nature last year, we may well be on our way to that end. Researchers at George Washington University in Washington, D.C reportedly discovered a superconductor that works at -13C (8F), although it has the caveat of working at a pressure equivalent to two million atmospheres. Nevertheless, this breakthrough is a superconductor that exists in a realistic temperature range for humans, and is the first in what will likely be a long line of incremental steps towards a room temperature superconductor.
The team used what they described as a “novel approach” to create a new superconducting structure. First, they created a mixture of lithium and hydrogen molecules, which were then compressed using diamond anvil cells, which compress a sample by pressing the tips of two diamonds together. The sample was then moved into a container designed to withstand high pressures. Then, they carried out the creation of the structure while maintaining at high pressures. By selectively firing a specially modified laser at the sample, they increased the temperature and pressure as they observed changes in conductivity.
The results were promising but challenging. As with many early stages of pioneering research, technology limits the scientist’s ability to truly understand their research. Due to the complexity of the experiment and the experimental design, temperature was not plotted with pressure; as such, exact figures on how the resistance changed with pressure are impossible to determine. Moreover, the resistivity of the original sample (from which the superconducting structure was created) was not determined, due to its complexity.
Nevertheless, the work being done by teams at George Washington University and elsewhere show a promising future in superconductivity. It represents the holy grail of solid state matter physics. But it’s also refreshingly un-esoteric; its worth to humanity cannot be overstated. The moment we have a room temperature superconductor is the “a-ha” moment for renewable energy, super high speed transportation, and maybe even flying cars.
Somayazulu, M., Ahart, M., Mishra, A. K., Geballe, Z. M., Baldini, M., Meng, Y., . . . Hemley, R. J. (2019). Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures. Physical Review Letters, 122(2). doi:10.1103/physrevlett.122.027001