Strain doubles superconductor temperatures
Jul 30, 1998
European researchers have developed a technique that can double the temperature at which some copper oxide compounds are superconducting. Jean-Pierre Locquet of IBM Research in Zurich and colleagues used compressive strain in thin films to boost the transition temperature, Tc, from 25 K to 49 K (Nature 394 453).
Their technique works by growing single crystal films of the superconducting compound lanthanum-strontium-copper-oxide (La1.9Sr0.1CuO4) on top of a crystal with a smaller lattice spacing. Because the layers are very thin, the layer of superconductor is placed under 'epitaxial' strain. The compression in a single plane produces much greater improvements in Tc than standard ways of applying pressure.
If the same techniques can be applied to the compounds with the highest transition temperatures, the authors believe their method has the potential to raise Tc beyond 200 K, a feat they hope might reignite the race towards room-temperature superconductivity.