Voltage relaxation and Abrikosov–Josephson vortices in Bi-2223 superconductors doped with α-Al2O3 nanoparticles

Magnetic relaxation in (Bi, Pb)-2223 superconducting ceramics doped with α-Al2O3 nanoparticles

“…From Table III it can be noticed the confirmation of the result interpreted from Table II and it is the fact that from this analysis the sample B05 in pellet form has the highest pinning energy for 300 Oe, value of the intensity of the applied magnetic field where it is supposed that the crystals have been totally penetrated. It could be thought that the lack of correspondence between the pinning energies measured for the samples by the electric transport route [19] and by the magnetization relaxation route presented in this paper (see Table III) reveal that the two results are counterposed. The cause of this interesting physical fact is explained below.…”

“…In the case of the latter, the result provides information of the pinning in the whole sample, but having been totally penetrated the crystallites, so that the three types of vortices contribute to the result and, as in this case, no current is applied to the sample, all the vortices that penetrated and were trapped in each of the regions (or different levels of superconductivity) remain either by the effects of the presence of intragranular planar defects [14][15][16][17] or by the presence of α-Al 2 O 3 nanoparticles (pores). Such an effect that is revealed in the behavior of the B05 sample in pellet form, is impossible to detect from transport measurements, for only taking into account that a current is applied to the sample the conditions are modified and the effects of that modification influence especially in the J that have the lower energies and by the action of the Lorentz force are expelled from the material even without being able to be detected for values of intensity of the applied magnetic field less than 300 Oe [19].…”

“…The cause of this interesting physical fact is explained below. For transport measurements it is sample B03 it is the one with the best properties because it has the highest pinning energy values [19], while for the magnetic relaxation, sample B05 in pellet form that has the highest pinning energy value. In the case of the latter, the result provides information of the pinning in the whole sample, but having been totally penetrated the crystallites, so that the three types of vortices contribute to the result and, as in this case, no current is applied to the sample, all the vortices that penetrated and were trapped in each of the regions (or different levels of superconductivity) remain either by the effects of the presence of intragranular planar defects [14][15][16][17] or by the presence of α-Al 2 O 3 nanoparticles (pores).…”