2D Crystals Could Support Superconductivity
Superconductivity is a phenomenon many in the world have been waiting anxiously for, but achieving it is difficult. Typically the materials that can become superconducting must be cooled to very low temperatures, but the hope is to one day find or design one that would work at room temperatures. Researchers at the University of California, San Diego have recently discovered an artificial crystal structure that should support superconductivity, and the principle behind it.
The structure the researchers describe is comprised of alternating layers of atomically thick layers of semiconductor and insulator. Specifically they describe the molybdenum disulfide as the two-atom thick semiconductor, with boron nitride being the few-atom thick insulator separating and cladding the semiconductor. When an electric field is applied to this structure, electrons and holes, the positively charged areas left behind by electrons, collect in the different semiconductor layers. Despite the separation, the electrons and holes are still bounded, forming indirect excitons. At a certain temperature, these excitons will achieve the coherent state of superfluidity, meaning that they will form a gas lacking any viscosity. This will also cause the phenomenon known as counterflow superconductivity.
What this all translates to is a blueprint for creating structures that become superconducting at a specific temperature. Presently that temperature is predicted to rest near that of other high-temperature superconductors, which is still pretty cold. As the blueprint can be applied to other materials though, it could lead to new understanding of superconductivity and other quantum phenomena.