Strongly enhanced irreversibility fields and Bose-glass behaviour in bulk YBCO with discontinuous columnar irradiation defects

Abstract

Flux pinning properties and irreversibility fields Birr(T) of melt-textured YBCO with discontinuous or multiple-in-line-damage (MILD) columnar defects produced by irradiation with high-energy U238 ions were studied at a constant matching field of Bϕ = 10 T and for several energy losses between Se = 1.67 and 2.4 keV Å−1. With increasing Se and increasing length of the MILD pins, the critical current density jc(H,T) strongly increases and Birr(T) for fields along the c axis progressively shifts upwards reaching 9 T at 77 K. For Se = 2.4 keV Å−1, a pronounced kink is observed in Birr(T) at 8 T which is a strong indication of Bose-glass behaviour. The jc(H) dependence of this sample shows a peak at a low applied field Bp. This peak effect is explained by the entanglement of vortices. It is argued that for MILD pins single vortices interact simultaneously with many short columnar defects in neighbouring ion trails resulting in an automatic splay in the vortex orientation. The observed decrease of Bp with increasing temperature is estimated taking the increasing thermal fluctuations into account.

Critical current density and flux pinning in Zr0.96V0.04B2 superconductor with AlB2 structure

“…28 Furthermore, the irreversible regions lie at much lower fields than the upper critical fields, H c2 (T), determined from the electrical transport measurement, 23 which is usually observed in high-T c superconductors or in superconducting samples with weak pinning. [29][30][31] The double-logarithmic plots for the J c (H) shown in the inset of Fig. 3 suggest that the pinning mechanism for the Zr 0.96 V 0.04 B 2 is probably associated with collective pinning, if one takes into account the power law J c (H) / H Àb in the slope regions indicated in Fig.…”

The cause of ‘weak-link’ grain boundary behaviour in polycrystalline Bi2Sr2CaCu2O8and Bi2Sr2Ca2Cu3O10superconductors

“…An improvement in flux pinning was seen in proton irradiated sintered ceramic pellets of YBCO and Bi2Sr2Ca2Cu3O10 by Mezzetti et al [74], and in ion irradiated melt-textured YBCO with a high concentration of discontinuous columnar defects by Fuchs et al [75]. However, Behera et al [76] found that swift heavy ion irradiation of YBCO granular thick films damaged grain boundaries, and Eisterer et al [77] found that neutron irradiation of YBCO coated conductors found no improvements.…”

Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

“…4,5) When CDs are shortly segmented (i.e. discontinuous), on the other hand, the linearity and the discontinuity of the CDs provide more effective flux pinning in a wide angular range: the ends of the discontinuous CDs act as effective PCs except for B || c, [6][7][8] while a sort of splay effect is induced due to the existence of gaps in the segmented CDs at B || c. 9) Moreover, reduction of the superconducting area due to the presence of PCs can be minimized for discontinuous CDs, which leads to an upward shift of the absolute J c value in the whole angular region. [7][8][9] Therefore, discontinuous CDs can be one kind of promising PCs to approach the pair-breaking critical current density.…”