Sensitivity of the thermomagnetic instability in superconducting film to magnetic perturbation for electromagnetic interference detection

The time-varying magnetic field with electromagnetic perturbation is regarded as an important parameter for the thermomagnetic stability of superconducting film devices. In this work, using a thermomagnetic model, we investigate the sensitivity of thermomagnetic instability in superconducting films exposed to a linear ramp magnetic field, superposed by the additional AC magnetic perturbation with tunable amplitude and oscillation frequency. Surprisingly, we find that the thermomagnetic instability is a non-monotonic function with the increasing oscillation frequency of the magnetic perturbation, depending on the working temperature and oscillation amplitude. The unexpected non-monotonic sensitivity of the thermomagnetic instability is revealed by the characteristic oscillation of the electric field, which cannot be aggravated by the AC magnetic perturbation at very high frequencies. The findings of this paper demonstrate that the magnetic perturbation at very low or high frequencies is not the main factor that triggers the thermomagnetic instability of superconducting films. Furthermore, using the magnetic moment measurement, we propose possible electromagnetic interference detection by the superconducting film based on such non-monotonic sensitivity of the thermomagnetic instability, which can be used to detect the tunable target electromagnetic interference with characteristic frequency in a complex electromagnetic environment.