The Proximity and Josephson Effects in Niobium Nitride–Aluminum Bilayers

Abstract

Highly disordered thin films of niobium nitride and the specific features of the proximity effect in NbN (S)–aluminum (N) bilayers with a large resistivity ratio, ρ_NbN/ρ_Al\( \gg \) 1, are studied. It is shown that magnetic screening and the critical current I_c of such SN structures significantly increase compared to the S layer. The observed effect is associated with the induced superconductivity in the N layer due to the proximity effect. The Josephson effect is demonstrated in NbN/Al–NbN–NbN/Al variable thickness bridges made of such SN bilayers.