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

TL;DR

This paper analyzes how magnetic fields affect the critical current in 0, Pi, and 0-Pi Josephson junctions, revealing effects of asymmetry and flux penetration related to magnetic properties and fabrication methods.

Contribution

It provides a detailed analysis of magnetic interference patterns in 0-Pi Josephson junctions, highlighting the impact of asymmetry and flux penetration on critical current behavior.

Findings

Fraunhofer pattern observed in 0 and Pi junctions

Finite critical current at the central minimum in 0-Pi junctions due to asymmetry

Asymmetric maxima and bumped minima in I_c(B) patterns

Abstract

We present a detailed analysis of the dependence of the critical current I_c on the magnetic field B of 0, Pi, and 0-Pi superconductor-insulator-ferromagnet-superconductor Josephson junctions. I_c(B) of the 0 and Pi 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-Pi 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 Pi 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 Pi 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-Pi junctions.