Individual Shapiro steps observed in resistively shunted intrinsic Josephson junctions on Bi2Sr2CaCu2O8+x single crystals

With a thin gold layer, we fabricated mesa-like shunted intrinsic Josephson junction stacks on Bi2Sr2CaCu2O8+x single crystals. Instead of the multibr anch structure and large voltage jumps often observed in conventional intri nsic junctions, current-voltage characteristics typical of resistively shun ted junctions were obtained. Individual Shapiro steps were clearly visible with irradiation at frequencies from a few to 20 GHz. The experiments demon strated not only the ac Josephson effects directly but also the possibility of employing intrinsic Josephson junctions in high-frequency applications. (C) 2000 American Institute of Physics. [S0003-6951(00)00533-7].