0-$\pi$ transition driven by magnetic proximity effect in a Josephson junction

TL;DR

This paper theoretically demonstrates a controllable 0-$$ transition in a superconductor/normal metal/superconductor Josephson junction induced by magnetic proximity effect and magnetic configuration switching, with potential applications in superconducting electronics.

Contribution

It reveals how magnetic proximity effect and spin valve configurations can reversibly switch the 0-$$ state in Josephson junctions, advancing control in superconducting devices.

Findings

0-$$ transition occurs with increasing N thickness due to magnetic proximity effect.

Switching between 0 and  states is possible by changing ferromagnetic magnetization configuration.

The transition can be observed experimentally with current nanofabrication techniques.

Abstract

We theoretically study the Josephson effect in a superconductor/normal metal/superconductor ({\it S}/{\it N}/{\it S}) Josephson junction composed of $s$-wave {\it S}s with {\it N} which is sandwiched by two ferromagnetic insulators ({\it F}s), forming a spin valve, in the vertical direction of the junction. We show that the 0-$\pi$ transition of the Josephson critical current occurs with increasing the thickness of {\it N} along the junction. This transition is due to the magnetic proximity effect (MPE) which induces ferromagnetic magnetization in the {\it N}. Moreover, we find that, even for fixed thickness of {\it N}, the proposed Josephson junction with the spin valve can be switched from $\pi$ to 0 states and vice versa by varying the magnetization configuration (parallel or antiparallel) of two {\it F}s. We also examine the effect of spin-orbit scattering on the Josephson critical current and argue that the 0-$\pi$ transition found here can be experimentally observed within the current nanofabrication techniques, thus indicating a promising potential of this junction as a 0-$\pi$ switching device operated reversibly with varying the magnetic configuration in the spin valve by, e.g., applying an external magnetic field. %with the magnetization configuration in the spin valve. Our results not only provide possible applications in superconducting electronics but also suggest the importance of a fundamental concept of MPE in nanostructures of multilayer {\it N}/{\it F} systems.