Superconducting materials are themselves not exactly rare in the modern age. A great deal of research has been put into developing better superconductors in the search for the elusive room-temperature superconducting material. Why are scientists working so diligently towards this fabled matter? One of the so-called high-temperature superconducting materials with the highest known Tc, or critical temperature is a ceramic material composed of thallium, mercury, copper, barium, calcium, strontium and oxygen -- it reaches this point at a record setting 138 degrees Kelvin (-211.27 Fahrenheit).
While this is arguably better than the first discovered superconductors, which switched states at around 20 K (-423 F), it still prevents superconductors from finding their way into household electronics and large scale power systems, just to name a few, where their presence would revolutionize their respective industries entirely.
Researchers at the Carnegie Institute of Science and Stanford University are looking in another direction to study the mystery of the superconducting state. The group has been observing what happens to superconductors above their Tc when under extreme pressures. They used a bismuth-based cuprate, or ceramic copper oxide, which many high-temperature superconductors are based on, and studied the changes the matter underwent as pressure increased. Their observations will be published in the May 30th issue of Physical Review Letters.
"Pressure has the added bonus that it can be applied gradually, like tuning a radio. We gradually tuned in to the superconductivity and could watch what happened over a broad range of pressures," explains one of the paper's co-authors, Alexander Goncharov of Carnegie's Geophysical Laboratory. Using a diamond anvil, the group brought the test samples up to a pressure of 35 Gigapascals, or 350,000 times atmospheric pressure at sea level. Using Raman spectroscopy and X-ray diffraction to measure the changes in the sample as it underwent pressurization, they found that the sample's state switched to superconducting at around 21 GPa.
While it's highly unlikely that electronic appliances will soon feature high-pressure circuitry, the group's work opens new doors into superconductivity research. Studying the interaction of the materials at the atomic level while under pressure may provide insight into how scientists can tweak new materials to achieve even higher Tcs and work towards bringing the still mythical room-temperature superconductor to life.