Periodic oscillations of flux flow resistance in intrinsic Josephson junctions with various lateral sizes down to a size of non-linear core of Josephson vortex

To investigate in-phase structures (rectangular lattice) of Josephson vortex lattice (JVL) in intrinsic Josephson junctions (IJJs) of Bi2Sr2CaCu2O8+d, we fabricated IJJs with various lateral sizes down to a size of non-linear core of Josephson vortex using focused-ion-beam etching and measured flux flow resistance (RFF) with in-plane magnetic fields (H). We have found that above a size-independent critical field, the critical current shows Fraunhofer pattern in narrow-length IJJs (0.29-2.77 mm), and then the RFF~H oscillates with H0 period. Most strikingly, such oscillations become pulse-like in sub-micron IJJs, indicating that between the pulses, the rectangular JVLs become major structures.