Abstract
We report on spatially resolved measurements of dynamic states of Josephson tunnel junctions in an external magnetic field. Using low-temperature scanning electron microscopy we imaged the beam-induced change of the maximum Fiske-step currents and the voltage change of current-biased step states. The excitation of one- and two-dimensional self-resonant cavity modes is clearly visible with a spatial resolution of about 3 \ensuremath{\mu}m. We used a 50\ifmmode\times\else\texttimes\fi{}50 \ensuremath{\mu}${\mathrm{m}}^{2}$ Nb/${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$/Nb tunnel junction representing a junction of intermediate size. Our experimental results agree well with a qualitative model for the signal generation based on the global change of the junction quality factor Q due to the local electron-beam irradiation. In addition, we present results of a calculation based on the perturbed sine-Gordon equation that takes into account the suppression of the critical current density in the area of the electron beam irradiation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
