Electronic properties of the superconducting cuprates

New and fundamental properties of the normal and superconducting states of the cuprates have been discovered recently. Low temperature-high field experiments have shown a semiconducting behaviour, suggesting that their normal state is not metallic. Interference experiments are in favor of a superconducting state having a d-wave symmetry. Further work is necessary to establish more firmly these discoveries and to find out how general they are amongst high Tc superconductors.