The influence of vanadium oxide on the properties of Josephson tunnel junctions

Abstract

The properties of VNb–NbOx–Pb and NbV–VOx–Pb Josephson tunnel junctions are investigated. The behaviour of the VNb–NbOx–Pb junctions is as expected for tunnels with proximity effect. The junctions with the VOx barriers have anomalous small critical currents and very large excess currents. Both, the temperature dependence of the critical current and the excess current of these junctions deviate strongly from that of other known tunnel junctions. The interaction of the tunneling electrons with strong internal magnetic fields within the VOx is discussed as a possible reason of these deviations.

Tunneling into Proximity Electrodes with Magnetic Impurities

“…The modifications of the tunneling density of states caused by the magnetic impurities produce strong deviations from the generally known current-voltage characteristic. The quasiparticle current demonstrated here is similar in both frequency dependence and temperature dependence to the experimental results gained from V/Pb tunnel junctions [22] but also from some Nb/Pb tunneling systems [13 to 15, 23, 241. It is well known that the fabrication caused surface layer near the tunneling barrier contains different oxides of the basis electrode material [25].…”