Shapiro Steps in Flux-Trapped Surface Intrinsic Junctions of Bi₂Sr₂CaCu₂O_8+δ

Microwave-field responses of the surface intrinsic Josephson junctions (IJJs) of Bi₂Sr₂CaCu₂O_8+δ superconductors are investigated. The IJJs are fabricated using an in situ low-temperature cleavage technique, which leads to the well-characterized surface CuO₂ double layers and surface junctions. For the surface junctions in the large-junction limit, usually no Shapiro steps appear when a microwave field is applied. It is found that when the junctions are in a flux-trapped state, which is produced by a pulsed current and in which the critical current is significantly suppressed, clear Shapiro steps can be observed. These results are important for the study of the microwave-field properties of vortex-carrying IJJs and may find their use in device applications.