Investigation of thedB/dHeffect using trapped flux in type-II superconductors

Effect of the configuration of the trapped flux on the decay rate of remanent magnetic moments in type II superconductors

“…In that paper, Blinov et al display the growth of M B over the entire low-field S-shaped region and the plateau of M B which is observed when the excursion of H 0 exceeds the 'double' penetration field H * * (see figure 2(d ) of [9]). The latter is the amplitude of the applied field sweep needed to establish flux-retaining currents circulating around the entire volume of the specimen after its removal [23,24].…”

“…For completeness, in figure 9 we display theoretical and also for comparison with the corresponding data of Blinov et al [1] (their figures 6 and 7). The appropriate formulae are given in the appendix of [23]. We note from these comparisons that the initial rapid rise observed for M B versus H 0 is better described by exploiting the Kim dependence of j c on B than by the Bean-London approximation.…”

Disclosure of hidden magnetic moments in low and highTchysteretic and semi-reversible type II superconductors during warming toTc

“…This quantity will constitute the only adjustable parameter introduced in our modelling of the magnetization curves and thermal evolution of the very hysteretic samples we have examined. The physical meaning of the labels 'first' and 'double' penetration fields emerges from consideration of the sequences of flux density profiles which occur as an isothermal sweep of H a causes the locus of M to trace the magnetization curves mentioned above [15][16][17][18].…”

“…Here the trapped flux is termed residual or remanent. Two simple prescriptions, denoted H cool and H cycle , have been exploited to establish a critical remanent magnetized state [14][15][16]. In the H cool procedure, the specimen is first made to undergo field cooling to the selected temperature T 0 in a magnetic field H a , denoted H cool .…”

“…application and removal of a magnetic field H a , then labelled H cycle . To ensure that this procedure causes the entire specimen to be filled with flux retaining persistent currents in the remanent magnetized state, H cycle must exceed a threshold value, denoted H * * (T 0 ), where H * * (T 0 ) > H * (T 0 ) [14][15][16].…”