Behavior of bulk melt-textured YBCO single domains subjected to crossed magnetic fields

Abstract

Abstract-We have experimentally investigated the crossed magnetic field effects on bulk melt-processed YBCO single domains. The samples were first permanently magnetized along their -axis and then subjected to several cycles of a transverse magnetic field parallel to the planes. The magnetic properties along the and directions were simultaneously measured using a couple of orthogonal pick-up coils as well as a Hall probe placed against the sample surface. The effects of both sweep amplitude and polarity were investigated. Field sweeps of alternate polarities are shown to affect the decay of the -axis magnetization much more strongly than field sweeps of unique polarity do. However, the -axis magnetization does not show any saturation even after a large number of field sweeps. Next, a micro-Hall probe scanning system was used to measure the distribution of magnetic induction over the top surface of the single domain subjected to the same combination of magnetic fields. The results are shown to be consistent with those determined with the sensing coils and bring out the role played by geometric effects.

Remagnetization of bulk high-temperature superconductors subjected to crossed and rotating magnetic fields

“…The collapse in magnetization shown in Fig. 1(b) is also qualitatively similar to that reported in the literature [13][14][15][16][17] and to Hall probe measurements performed on larger samples of the same material [18,31].…”

“…In each case, the magnetic moment is normalized with respect to its initial value. The (N=1) measurements refer to the remaining magnetic moment after the first application of the transverse field; the corresponding values decrease as the field amplitude increases, as expected [18]. In all cases, the first magnetic field rotation increases the magnetic…”

“…3(a) that the (N=1) data points in each sequence are very close to each other since they result from the application of the same 0.5 H p transverse field. A subsequent series of transverse field cycles only ("Strans") leads to a monotonic decrease of the magnetization, as is observed usually [14,17,18]. Applying a magnetizing field pulse parallel to the initial direction of magnetization between each transverse field cycle ("S-rem") yields a slightly less pronounced decay in magnetization.…”

Measurements of Thermal Effects in a Bulk YBCO Single Domain Superconductor Submitted to a Variable Magnetic Field

“…at and . A bulk YBCO cylindrical pellet was mounted with the following sensors, as schematically shown on type thermocouples attached to the top surface and located at several distances from the center, (ii) two AREPOC Hall probes (active surface 2 mm 3 mm) placed against the sample bottom surface and (iii) a pick-up coil closely wound around the lateral surface [19]. The two Hall sensors probe the -axis local magnetic induction respectively at the centre and at 1.5 mm from the sample edge.…”

Demagnetization of Cubic Gd-Ba-Cu-O Bulk Superconductor by Crossed-Fields: Measurements and Three-Dimensional Modeling

“…There are several studies of cross-field demagnetization. Those involve 2D FEM modelling using the H formulation and experiments [16], [17], the study of hybrid (ferromagnetic/superconducting) structures by 2D and 3D modelling and experiments [18], and the comparison of numerical calculation based on A and H formulation (FEM) with theory of Brandt and Mikitik (thin strip) [19].…”