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.

Surface energy and magnetocapacitance of superconductors under electric field bias

“…according to the thick sample limit of surface energy, (27) and (28), and the induced contribution due to diamagnetic currents, (40). In the following we will discuss them separately.…”

“…Here we outline the derivation of the domain wall parameter (28) without external bias b ∞ and for the situation of normal-superconducting boundaries as it is usually found in literature. 45,51,52 In terms of (9) the nonlinearized equation (3) reads…”

“…to test spin-dependent electrochemical potentials. Starting from the early reports on an increase of the capacitance 27 for superconducting tunneling junctions 28 , the residual surface resistance of superconducting resonators is still under discussion 29,30,31 since it becomes important for the question how short the electron bunches can be in free electron lasers before the generated wake fields disable the superconducting cavities. 30 Different mechanisms for such electron losses have been discussed in 31 .…”