Explaining high-Tc superconductors

Even a decade and a half after the discovery of high-temperature superconductivity in ceramic compounds containing copper-oxide planes, these materials continue to puzzle condensed-matter theorists. The challenge is not simply to find a reasonable formula that predicts the uniquely high values for the superconducting transition temperature in the cuprates. Rather, superconductivity is but one aspect of the unique and complex phase diagram exhibited by this class of materials. Depending on the temperature and the level of doping, the cuprates can be insulators, metals or superconductors. The non-superconducting or ''normal'' phase also exhibits unusual properties. (UK)