Frequency Dependence of the a c Josephson Effect in Small Dayem Bridges

Abstract

The current-voltage characteristics of superconducting thin-film indium microbridges (Dayem bridges) and their microwave-induced constant-voltage steps have been investigated at several frequencies. The results are well described by a resistively shunted Josephson junction model, which differs from the usual resistively shunted Josephson junction model only in having a current-phase relation of the form $I={I}_{0}(\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\phi}}) sin\ensuremath{\phi}+{I}_{1}(\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\phi}})\ifmmode\times\else\texttimes\fi{}cos\ensuremath{\phi}+{I}_{2}(\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\phi}})$, where the functions ${I}_{0}$, ${I}_{1}$, and ${I}_{2}$ are derived from time-dependent Ginzburg-Landau theory.