Nonlinear Electrodynamics of Superconducting Films

Abstract

Microwave-transmission measurements at 9.4 Gc/sec over a wide range of incident power have been used to study the nonlinear electrodynamics of thin superconducting films. By measuring the amplitude and phase of the fundamental transmitted field, the contributions of superelectrons and normal electrons to the electrodynamics of the films have been determined. In low microwave fields the nonlinear behavior of the films can be attributed to the breakup of superconducting pairs in agreement with the Ginzberg-Landau theory. In high microwave fields, regions of normal resistance appear through which a dc bias current cannot avoid passing. Most of the third-harmonic power is generated by these resistive regions.