Magnetic interference patterns in 0-Pi SIFS Josephson junctions: effects of asymmetry between 0 and Pi regions

Abstract

We present a detailed analysis of the dependence of the critical current Ic on the magnetic field B of 0, π, and 0-π superconductor-insulator-ferromagnet-superconductor Josephson junctions. Ic(B) of the 0 and π junction closely follows a Fraunhofer pattern, indicating a homogeneous critical current density jc(x). The maximum of Ic(B) is slightly shifted along the field axis, pointing to a small remanent in-plane magnetization of the F-layer along the field axis. Ic(B) of the 0-π junction exhibits the characteristic central minimum. Ic however has a finite value here, due to an asymmetry of jc in the 0 and π part. In addition, this Ic(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.

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

“…This effect, which is not reproduced by the simulated curve, is due to the finite magnetization of the F-layer which, in addition, is different in the 0 and π parts. This effect is addressed elsewhere [48].…”