Tunnel effect in films of vanadium and its oxides

Self Cite

Al‐insulator—Pb tunnel junctions with barriers produced in a glow discharge of CO2 or CO are studied. It is shown that for the first case a barrier is similar in its composition to those prepared using the plasma oxidation technique but contains molecules of the chemisorbed formic acid. HCOOH is found to be formed due to the organic synthesis in the glow discharge. In the second case there are junctions with barriers of 0.25 to 0.3 eV height. Certain assumptions of the barrier composition are made.

Studies on Al—insulator—Pb tunnel junctions with barriers prepared in glow discharge of CO2 and CO

Shklyarevskiǐ

Lysykh

Yanson

1976

Self Cite

A study of VVOxPb Josephson tunnel junctions

Dettmann

Blüthner

Pertsch

et al. 1977

The current-voltage characteristics and especially the behaviour of the critical Josephson currents of V-V0,-Pb tunnel junctions are investigated experimentally. The maximum Josephson current and its temperature dependence deviate strongly from the theory. The London penetration depth of the vanadium films is found to be much larger than for pure vanadium but its temperature dependence is as expected from theory. The critical temperatures of the vanadium films are between 4.4 and 5.0 K. The ratio 2A(0)/(kFc) decreases with decreasing critical temperature as in the case of superconductors with paramagnetic impurities. The excess currents in the current-voltage characteristics of the tunnel junctions at low voltages are not related to the critical temperatures of the vanadium films. Die Strom-Spannungs-Kennlinien und besonders das Verhalten des kritischen Josephsonstromes von V-V0,-Pb-Tunnelverbindungen werden experimentell untersucht. Der maximale Josephsonstrom und seine TempcraturabhLngigkeit weichen stark von der Theorie ab. Die Londonsche Eindringtiefe der Vanadinschichten ist wesentlich groBer als die fur reines Vanadin, ihre Temperaturabhiingigkeit stimmt jedoch mit der Theorie uberein. Die kritischen Temperaturen der Vanadinschichten liegen zwischen 4,4 und 6,O K. Das Verhaltnis 2A(O)/(kT,) fallt mit abnehmender kritischer Temperatur, wie es fur den Fall eines Supraleiters mit paramagnetischen Verunreinigungen erwartet wid. Die GroBe der VberschuBstrome in den Strom-Spannungs-Kennlinien der Tunnelverbindungen bei geringen Spannungen hangt nicht systematisch von der kritischen Temperatur der Vanadinschichten ab.

Properties of quantum interference devices with VVOxPb tunnel junctions

Dettmann

1978

The properties of double contact quantum interference devices (SQUIDs) with VVOxPb tunnel juctions are studied experimentally. With decreasing temperature an increasing hysteresis in the (I‐U) characteristics is observed. At lower temperatures there are multiple critical currents. At sufficiently low inductivities of the SQUID loop and small critical currents single valued critical currents can be reached. The dependences of the quantum interferences from magnetic field and from the temperature pointed out that small tunnel areas and a symmetric construction of the SQUID loop are advantageous.