The mechanism of nonlinear microwave behaviour inhigh-Tc superconducting devices

Abstract

First, this paper gives an overview of possible origins and mechanisms that might beresponsible for experimentally observed nonlinear effects. Focusing on well-known physicalloss mechanisms with nonlinear characteristics, their impact on microwave properties andtheir relevance in microwave devices are discussed. Secondly, an experimental investigationof the power handling capability of coplanar resonators in additionally applied dc magneticfields in zero field cooled, field cooled, and field sweep experiments is presented. Theseexperiments demonstrate that the microwave power handling capability of optimizedhigh-Tc thin film devices is limited by a maximum current density, andsuggest that the limitation is caused by the dc critical current densityJc of the superconducting material.