CRITICAL CURRENT DEPENDENCE OF STACKED JOSEPHSON JUNCTIONS DC SQUID IN Bi2Sr2CaCu2O8+Δ

Abstract

We investigate critical current (Ic) modulation of stacked Josephson junctions (SJJs) dc superconducting quantum interference device ( dc SQUID) on a Bi 2 Sr 2 CaCu 2 O 8+δ ( Bi -2212) whisker. A coupled SJJs with a completely perforated hole of 0.1 μ m × 0.2 μ m were fabricated by using a 3-D focused-ion-beam (FIB) etching method. Those dc SQUIDs exhibited uniform multi-branch structures and clearly oscillated critical current under external magnetic fields (He). With applying He, the clear periodic modulation patterns of Ic are obtained and well fitted to the calculated value from the loop area of 0.02 μm2.