Capacitance Effects in Superconducting Tunneling Junctions

Abstract

The present work describes measurements of the superconducting-tunneling-junction capacitance $C_g$, which show that $C_g$ increases when one of the junction metals undergoes a superconducting transition. $C_g$ increases as long as the temperature decreases, although at lower temperatures saturation of this effect seems to exist. Moreover, at fixed $T$, a sufficiently strong magnetic field restores the $C_g$ value, which is measured when both metals are in the normal state. This phenomenon seems to depend strongly on the insulating-layer thickness. A qualitative discussion of the experimental results in terms of the penetration of the electric field into the metal electrodes is given.