Superconductor On-Off Switch

European scientists have demonstrated that an electric field can turn on and off low-temperature superconductivity in a fabricated circuit (Nature 2008, 456, 624). This new capability is expected to lead to nanoscale superconducting (resistance-free) circuits that can be controlled by strategically located electric-field modulators. These scientists previously discovered that at the interface between two layers of oxide insulators, LaAlO₃ and SrTiO₃, a superconducting "electron gas" forms. Now, Andrea D. Caviglia and Jean-Marc Triscone of the University of Geneva and coworkers have made a field-effect transistor by depositing a layer of LaAlO₃ onto a SrTiO₃ crystal and adding other circuit components. When they induced an electric field in the device, they were able to control the electron density of the gas to switch between insulating and superconducting states. The paper "marks the dawn of a new era in the design of superconductors consisting of materials created with atomic-layer precision," say materials scientists Darrell G. Schlom of Cornell University and Charles H. Ahn of Yale University in a Nature commentary.