High Resolution Thermal Imaging of Hotspots in Superconducting Films

Thermal imaging of hotspots in bridge structures of YbaCuO thin films is presented with micrometer resolution. Hotspots formed by passing transport currents are observed using a method based on the temperature dependence in the photoluminescence of a polymer thin film deposited on the superconductor. The hotspots are self maintained and have hysteretic behavior. An external magnetic field changes their behavior. The temperature distribution over the bridge and in its vicinity can be observed with a resolution better than 0.1 K. Also details of the experimental method will be reported.