OBSERVATION OF BLOCH OSCILLATIONS IN GRANULAR TIN FILMS

Experimental observation of the 'Bloch oscillations' has been made in superconducting granular tin films. The values of 2ef, which have been obtained from the current intervals between voltages jumps/spikes on the voltage-current characteristics and the predicted relationship I = 2nef (n = integers), are in good agreement with the corresponding values calculated using a value of e = 1.60218 × 10-19 C and the frequency of applied microwave fields. The agreement has been improved to within 200 ppm as the absolute value of the current is calibrated at each run. It is not clear, as yet, whether the single-electron tunneling (SET) oscillations coexist in our data or not.