Nonsinusoidal current-phase relations and the 0−π transition in diffusive ferromagnetic Josephson junctions

G. Mohammadkhani; M. Zareyan

doi:10.1103/PhysRevB.73.134503

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Nonsinusoidal current-phase relations and the 0−π transition in diffusive ferromagnetic Josephson junctions

G. Mohammadkhani, M. Zareyan

DOI 10.1103/PhysRevB.73.134503 · Physical Review B

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Abstract

We study the effect of the interfacial transparency on the Josephson current in a diffusive ferromagnetic contact between two superconductors. In contrast to the cases of the fully transparent and the low-transparency interfaces, the current-phase relation is shown to be nonsinusoidal for a finite transparency. It is demonstrated that even for the nearly fully transparent interfaces the small corrections due to weak interfacial disorders contribute a small second-harmonic component in the current-phase relation. For a certain thicknesses of the ferromagnetic contact and the exchange field this can lead to a tiny minimum supercurrent at the crossover between 0 and π states of the junction. Our theory has a satisfactory agreement with the recent experiments in which a finite supercurrent was observed at the transition temperature. We further explain the possibility for observation of a large residual supercurrent if the interfaces have an intermediate transparency.