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. Near T_c the critical current varies with (1 - T/T_c^α), with a distribution of α values between 1 and 3/2. It is suggested that the α values can be used to characterize the bridges. The microwave enhancement of I_c and T_c was measured and these data were compared with a recent theory by Christiansen et al. on the microbridges. We found that their theory gives a correct prediction for the Dayem effect in the bulklike bridges (with α=3/2) while their theoretical values for the junction-like bridges (with α=1) are not in agreement with our data.