Superconducting phase transitions in quantum dots

In NdN and SdS nanostructures, anomalous ground states with a noninteger average number of electrons in the quantum dots d occur. These states correspond to pair or single-electron superconductivity and are separated from states with a definite (integer) number of electrons by, as a rule, second-order phase transitions. The characteristic features of the pair and single-electron superconducting Josephson current in SdS are discussed. (C) 1996 American Institute of Physics.