Thermal effects in microwave current-induced weak link switching in YBCO thin films

In this study, we have measured the microwave power dependence of the surface resistance (Rs) of a YBa2Cu3Ox (YBCO) thin film deposited on an LaAlO3 substrate up to superconductivityquenching microwave power levels. The time-domain technique was used to monitor the electromagnetic response dynamics of a 14 GHz TE011 dielectric sapphire resonator to pulsed microwave signals. Local and global heating induced nonlinearity was observed. This nonlinearity was analyzed using a simple analytical model to describe the charging process of the dielectric resonator in a YBCO thin film that included a single Josephson junction weak link. From the analysis of the switching-on weak links, we confirm the presence of heating on weak links even in the linear case and we also estimate that the local heating rate is of the order of a few microseconds.