Josephson effects in weakly coupled MgB2 intergrain nanobridges prepared by focused ion beam

摘要: We have fabricated weakly coupled intergrain nanobridges from MgB2 films by a focused ion beam (FIB) patterning technique and studied their transition properties. The bridges were nominally 300 nm wide 100 long, crossed single grain boundary perpendicularly. temperature-dependent resistance data showed two-step after FIB pattern with more-than-two-decade increase in the resistivity. Current-voltage curves characteristics of an ideal Josephson junction. measured perfectly matched theory resistively shunted junction model thermal fluctuations at all temperatures. At 4.2 K, effect hysteresis agreement estimated McCumber parameter βc>0.3. disappeared above 6 K. critical currents obtained fitting to RSJ linearly dependent on temperature, implying that played insulating barrier.