Stages of superconductivity
More than two decades after scientists discovered a new type of copper-based high-temperature superconductor — energy-efficient material that can carry electricity without waste — Harvard physicists say they have unlocked the chemical secret that controls its “fool’s gold” phase, which mimics, but doesn’t have all the advantageous properties of, superconductivity. In an effort to better understand the phase, called the “pseudogap,” Associate Professor of Physics Jenny Hoffman and Ilija Zeljkovic, a graduate student working in Hoffman’s lab, began studying where oxygen atoms — a critical element added (“doped”) to a copper-based ceramic to create the superconducting material —are located in the material’s crystal structure. As reported July 20 in Science, their surprising finding is that it isn’t oxygen, but a lack of it, that appears to be most strongly related to the pseudogap. The finding, Hoffman said, should give researchers the understanding to begin designing materials to act as superconductors at even...