Magnetic interference patterns in 0-π superconductor/insulator/ferromagnet/superconductor Josephson junctions: Effects of asymmetry between 0 and π regions

摘要

We present a detailed analysis of the dependence of the critical current I_c on an in-plane magnetic field B of 0, π, and 0-π superconductor-insulator-ferromagnet-superconductor Josephson junctions. I_C(B) of the 0 and the π junction closely follows a Fraunhofer pattern, indicating a homogeneous critical current density j_c.(x). The maximum of I_C(B) is slightly shifted along the field axis, pointing to a small remanent in-plane magnetization of the F-layer along the field axis. I_C(B) of the 0-π junction exhibits the characteristic central minimum. I_c, however, has a finite value here, due to an asymmetry of j_c in the 0 and the π part. In addition, this I_c(B) exhibits asymmetric maxima and bumped minima. To explain these features in detail, flux penetration being different in the 0 part and the π part needs to be taken into account. We discuss this asymmetry in relation to the magnetic properties of the F-layer and the fabrication technique used to produce the 0-π junctions.