An unusual magnetoresistance effect in the heterojunction structure of an ultrathin single-crystal Pb film on silicon substrate.

Superconductor films on semiconductor substrates have drawn much attention recently since the derived superconductor-based electronics have been shown to be promising for future data processing and storage technologies. By growing atomically uniform single-crystal epitaxial Pb films of several nanometers thick on Si wafers to form a sharp superconductor-semiconductor heterojunction, we have obtained an unusual magnetoresistance effect when the Pb film is superconducting. In addition to the large fundamental interest in this effect, the simple structure, and compatibility and scalability with current Si-based semiconductor technology offer a great opportunity for integrating superconducting circuits and detectors in a single chip.