Temperature dependence and microwave enhancement of the critical current of superconducting microbridges

The temperature dependence of superconducting tin, thin-film, narrow bridges has been investigated. NearT_c the critical current varies with (1 – T/T_c), with a distribution of values between 1 and 3/2. It is suggested that the values can be used to characterize the bridges. The microwave enhancement ofI_c andT_c was measured and these data were compared with a recent theory by Christiansenet al. on the microbridges. We found that their theory gives a correct prediction for the Dayem effect in the bulklike bridges (with =3/2) while their theoretical values for the junction-like bridges (with =1) are not in agreement with our data.Work supported in part by the National Science Foundation.