THE ANGULAR-DEPENDENCE OF CRITICAL-CURRENT DENSITIES IN BULK MAGNETICALLY MELT-TEXTURED YBACUO IN MAGNETIC-FIELDS UP TO 20 TESLAS

Bulk magnetically melt textured YBaCuO at 77 K shows critical current densities of up to 19000 A/cm2 in 20 teslas when the field is parallel to the (a, b) planes. The angular dependence of Jc is shown to support a recent interpretation of the high superconducting transport currents measured above the irreversibility line in terms of intrinsic surface superconductivity. The behavior when the field is applied very close to the (a, b) planes is shown to follow a two dimensional model meaning that the maximum current density is determined by the c-axis component of the applied field. The size and density of 211 inclusions are probably the main factors which determines the maximum critical current density.