PHOTOVOLTAIC EFFECT IN SMALL SUPERCONDUCTING-NORMAL-METAL SYSTEMS

We have observed an unusual photovoltaic effect in small metallic syst ems in which some portion of the sample is superconducting. In these s ystems, an applied microwave field can induce a de voltage (the ''phot ovoltage''), V-dc. We have found that this voltage can be an antisymme tric function of magnetic field, i.e., V-dc(+ H) = - V-dc(- H) It also exhibits aperiodic fluctuations as a function of both H, and the stre ngth of the microwave field. Results for several different sample geom etries suggest that it is due to the inverse Josephson effect, althoug h the samples are not obviously reminiscent of weak link structures.