Quenching Current by Flux-Flow Instability in Iron-Chalcogenides Thin Films

The stability against quench is one of the main issues to be pursued in a superconducting material, which should be able to perform at very high levels of current densities. Here we focus on the connection between the critical current Ic and the quenching current I ∗ associated to the so-called Flux-Flow Instability phenomenon, which sets-in as an abrupt transition from the flux flow state to the normal state. To this purpose, we analyze several current-voltage characteristics of three types of Iron-Based thin films, acquired at different temperature and applied magnetic field values. For these samples, we discuss the impact of a possible coexistence of intrinsic electronic mechanisms and extrinsic thermal effects on the quenching current dependence upon the applied magnetic field. The differences between the quenching current and the critical current are also reported in the case of predominant intrinsic mechanisms. Carrying out a comparison with the HTS case, we suggest, which material can be the best tradeoff between maximum operating temperature, higher upper critical field, and stability under high current bias.