Harmonic susceptibilities of polycrystalline (La1−xCax)(Ba1.75−xLa0.25+x)Cu3O7+d synthesized by amorphous metal-complex method

Grain geometry effect on the magnetic properties of a granular iron-based superconductor LaFeAsO1−xFx

“…In order to confirm or discharge this hypothesis, numerical simulations of magnetic flux diffusion in a superconducting slab have been performed (here we do not report the simulated curves, but details about the simulation technique used can be found in [37]). Moreover, the curves measured on the powder have been compared with many other curves obtained by numerical or analytical simulations in well-defined physical conditions [21,23,[30][31][32][33][34][35][36][37][38][39][40][41][42]. From this analysis it comes out that our third harmonics experimental curves are well reproduced by Youssef et al [30].…”

“…The presence of a state with irreversible magnetic properties produces nonlinear current-voltage characteristics which also induce nonlinearities in the magnetic response of the sample, giving rise to the appearance of harmonics higher than the first one [28,29]. In some cases, the third harmonic is also analysed, but differently from the first harmonic, its shape, as obtained with the help of numerical simulations or analytical calculations, changes dramatically depending on the geometry of the sample [21,23,30,31], on the vortex dynamic regimes [32][33][34][35][36][37], on the field and temperature dependences of the critical current density J c [38][39][40] and, in general, on some particular characteristics of the sample [41,42]. This suggests that the experimental third harmonics curves may help to discriminate among the various effects responsible for the detected magnetic response.…”