Electrical transport properties of Josephson junctions using polyimide Langmuir-Blodgett films

The authors prepared high-quality ultrathin multilayered films of polyimide (PI) on base-(noble metal) electrodes by the Langmuir-Blodgett (LB) technique and then fabricated tunnel junctions with structures of Au/PI/Au and Au/PI/(Pb-Bi). They also fabricated Josephson junctions consisting of PI LB films sandwiched between Nb/Au and (Pb-Bi) superconducting electrodes. Subsequently, they examined the electrical transport properties of the junctions. It was found that the electrical transport current flowing through the PI LB layers is ruled by the tunneling theory of the Bardeen-Cooper-Schrieffer theory. The inelastic electron tunneling spectroscopy spectra of the junctions show that electron tunneling through PI LB films is elastic