Title :
Investigation of double-barrier Nb-Al-AlO2-Al-AlOx -(Al-)Nb junctions under high-frequency irradiation
Author :
Nevirkovets, Ivan P. ; Ketterson, John B. ; Siegel, Michael
Author_Institution :
Dept. of Phys. & Astron., Northwestern Univ., Evanston, IL, USA
fDate :
3/1/2001 12:00:00 AM
Abstract :
We have studied experimentally the current-voltage characteristics of double-barrier Nb-Al-AlOx-Al-AlOx-(Al-)Nb junctions exposed to microwave radiation at 4.2 K. Both integer and fractional Shapiro steps were observed. A complicated behavior of the step heights was observed as a function of both the microwave power and an applied magnetic field. Reasonable agreement with the RSJ model was obtained only for the steps 0 to 2 observed in current-voltage characteristics of the junctions with a “clean” middle Al layer. A deviation from RSJ-like behavior was found for higher-order integer steps and fractional steps. Devices with a “dirty” middle Al layer displayed more significant deviation from RSJ-like behavior. Step heights vs. magnetic field dependences in some cases were found to be qualitatively different from the field dependence of the dc Josephson current
Keywords :
Josephson effect; aluminium; aluminium compounds; niobium; 4.2 K; DC Josephson current; Nb-Al-AlO-Al-AlO-Al-Nb; Nb-Al-AlO-Al-AlO-Nb; RSJ model; SINIS double barrier junction; Shapiro step; current-voltage characteristics; magnetic field; microwave irradiation; Artificial intelligence; Astronomy; Current-voltage characteristics; Josephson junctions; Magnetic fields; Microwave theory and techniques; Optical films; Physics; Superconducting devices; Superconducting microwave devices;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
