Gate-tunable nonlocal Josephson effect through magnetic van der Waals bilayers

Abstract: It is well-known that the proximity effect at superconductor/ferromagnet (S/F) interfaces produces damped oscillatory behavior of the Cooper pair wave function within the ferromagnetic regions, which is analogous to the inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity. It is often called the mesoscopic FFLO state and gives rise to $0-\pi$-transitions in S/F/S Josephson junctions. This paper offers an analysis of the proximity effect at interfaces between superconductors and magnetic van der Waals (vdW) bilayers. The specific feature of the proximity effect in the vdW bilayer systems is the presence of non-local Cooper pairs. We predict that the mesoscopic FFLO state formed by such pairs is sensitive to the difference between on-site energies of the monolayers composing the bilayer and, thus, can be controlled by applying a gating potential to one of the monolayers. This opens the possibility of implementing gate-controlled $0-\pi$ transitions in Josephson junctions through the magnetic vdW bilayer weak links.