DIMENSIONALITY AND PINNING OF MAGNETIC VORTICES IN THE C-AXIS ALIGNEDBI2SR2CACU2O8+DELTA AND (BI,PB)(2)SR2CA2CU3O10 AG TAPES IRRADIATED BY5.8-GEV PB IONS/

Powder-in-the Ag tube processed Bi2Sr2CaCu2O8+delta and (Bi,Pb)(2)Sr2C a2Cu2O10 tapes were irradiated with 5.8-GeV Pb ions along the tape nor mal for the ion fluences of 0.68, 1.0, and 2.0 X 10(11) cm(-1). The an gular (theta) dependence of critical current densities J(c)(theta,B,T) for these tapes was measured at temperature T=27 K and 55-80 K, Cuspl ike sharp peaks in J(c)(theta,B,T) were observed for T greater than or equal to 55 K when the applied magnetic field B is oriented parallel to the direction of the irradiation (theta=90 degrees), and J(c)(theta ) did not scale with the perpendicular component of B, (B-perpendicula r to=B sin theta). Based on this evidence, it was concluded that the m agnetic vortices behave as linelike (three-dimensional) rather than th e pancakelike [two-dimensional (2D)] objects in these irradiated super conductors. However, at 27 K, neither the peaks in J(c)(theta) nor the scaling of J(c)(theta) with B-perpendicular to was observed. We attri bute this to the increased strength of the isotropic pinning by the sm all irradiation-induced defect debris relative to that of the columns and due to the increased interlayer coupling strength at reduced tempe rature, but not as evidence for the pancakelike 2D vortices at low tem peratures, Also, for T greater than or equal to 55 K, the enhancement in the pinning strength qualitatively followed the theory by Nelson an d Vinokur [Phys. Rev. Lett. 68, 2398 (1992); Phys. Rev, B 48, 13 060 ( 1993)].