Mixed state properties analysis in AC magnetic field of strong pinning Fe(Se,Te) single crystal

The fundamental harmonic of the AC magnetic susceptibility of a Fe(Se,Te) single crystal iron based superconductor has been studied at different AC field amplitudes and frequencies with and without a superimposed DC magnetic field with the aim of analyzing its superconducting properties that can be also suitable for power applications such as the critical current density and the pinning energy in AC regime. From the analysis of the fundamental Cole-Cole plots a finite influence of flux creep phenomena has been detected. Its study, by means of the Arrhenius plots, evidences thermal activation energy U values as high as 103 K, whose dependence on the DC and AC fields, and of the temperature, has been also obtained. The magnetic field dependence shows the existence of the strong pinning regime characterized by plastic deformations of the vortex lattice, whereas the temperature dependence of the critical current density Jc(T) is consistent with the δl pinning model. Finally, the irreversibility field values Hirr(T) have been extracted from the Jc(T) at the different AC frequencies showing very high values if compared with the literature.