Numerical study of multi-hole SQUIDs using Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions

The I-V characteristics and the resultant total energies have been calculated full numerically for the parallel arranged multi-hole superconducting quantum interference devices (SQUIDs) consisting of Bi2Sr2CaCu2O8+δ high-Tc superconductors intrinsic Josephson junctions (BSCCO-IJJs). It has been found that (I) the effect of charge coupling between neighboring Josephson junctions is not so important, (II) the effect of noise is not so crucial except for the case of low βL and no external magnetic field, and (III) a reliable external magnetic field dependence is obtained when the βL is less than about 0.5, where the βL is a dimensionless parameter defined by LloopIc/Φ0 using a loop inductance Lloop of a SQUID, a critical current Ic of a junction, and a flux quantum Φ0. We have pointed out that (IV) the steps which differ from Shapiro steps are found when an external ac modulation current is applied to the parallel arranged multi-hole SQUIDs, and (V) the I-V characteristics of a double hole BSCCO-IJJs-SQUID trapping a flux quantum can be controlled as a function of the external magnetic field.