Intermodulation distortion in HTS thin films: a global heating model

The non-linear microwave response of high transition-temperature superconductors (HTS) thin films is a critical issue for applications of the cuprates in future communications technologies. We report that the conventional figure of merit, the third-order intercept, does not provide a good measure of performance for HTS materials. We describe a physical model for intermodulation distortion generation which arises from global heating effects in a thin film, not previously noted. We present results on a high quality YBCO thin film which support the validity of this model. Predictions are made of techniques to reduce the intermodulation in films of this quality.