Tunneleffekt an amorphen und stark gestörten Zinnschichten

We have performed tunnelmeasurements on evaporated tin‐films with various amounts of copper added. The tunneljunctions were evaporated and cooled down to helium temperatures in situ in a metal‐cryostat. Tin‐copper‐films, which are condensed at low temperatures, are amorphous. They have critical temperatures from 7 °K to 3,5 °K depending on the content of copper. Tunnelmeasurements indicate that the high transition temperature belongs to a superconductor with strong coupling, whereas the lower critical temperature is characteristic of a weak coupling superconductor. Structures in tunnelcharacteristics and transition‐curves indicate that a film can have several energy‐gaps and that regions with strong and weak coupling can exist in the films. — Describing the metal‐cryostat we point out that one can reach temperatures below 1 °K with small pumping rates by diminishing the Hell film flux.