Method for reliable realization of a varphi Josephson junction

TL;DR

This paper introduces a method to create a $$ Josephson junction with a stable $$ ground state by combining alternating 0 and $$ segments and considering non-sinusoidal current-phase relations, especially in ferromagnetic barriers.

Contribution

It presents a novel approach to realize $$ Josephson junctions by integrating non-sinusoidal CPR effects, expanding the feasible parameter space for stable $$ states.

Findings

Enlarged domain of $$ ground state with ferromagnetic barriers.

Feasible realization of $$ Josephson junctions in practical devices.

Multiple stable solutions including 0, $$, and $$-$$ states.

Abstract

We propose a method to realize a $\phi$ Josephson junction by combining alternating 0 and $\pi$ parts (sub junctions) with an intrinsically non-sinusoidal current-phase relation (CPR). Conditions for the realization of the $\phi$ ground state are analyzed. It is shown that taking into account the non-sinusoidal CPR for a "clean junction with a ferromagnetic (F) barrier, one can significantly enlarge the domain (regime of suitable F-layer thicknesses) of the $\phi$ ground state and make the practical realization of $\phi$ Josephson junctions feasible. Such junctions may also have two different stable solutions, such as 0 and $\pi$, 0 and $\phi$, or $\phi$ and $\pi$.