Enhanced current transport at grain boundaries in high-Tc superconductors

Against the grain Soon after the discovery of high-temperature superconductors in 1986, it became clear that their polycrystalline nature has an unfortunate consequence: the superconducting properties are compromised by an orders of magnitude reduction in the critical current across these interfaces. Much work has gone into attempts to remove such boundaries. But a recent report suggested that doping can enhance the grain boundary critical current by an order of magnitude, providing a simple route towards practical use of YBa2Cu3O7-δ as a high-temperature superconductor. Klie et al. present an atomic-scale description of the mechanism behind the dramatic improvement of grain boundary properties. This work should lead to rational guidelines for the choice of suitable dopants.