Novel experimental result contradicts conventional pinning theory; record-high Jc obtained by reducing the pinning potential

Abstract Scores of work have suggested that the pinning potential energy, U p , should be maximized to achieve high critical current density, J c . This has led several researchers to believe that the highest J c could only be achieved by means of continuous columnar defects, CCPCs, because they provide the largest U p . We now present the surprising experimental result that, in clear contrast with the conventional belief, J c for discontinuous pinning is much higher than for continuous. For example, in melt-textured YBCO we obtained a record-high J c  ∼ 275 kA/cm 2 , at B  = 1 T and T  = 77 K, using discontinuous multiple-in-line-damage, MILD. Our data contrary to conventional pinning theories indicate that J c does not depend primarily on U p , but on the simultaneous optimization of three factors: the loss in current percolation, the reduction in T c , and U p . In conclusion the maximum J c in YBCO, at 10 K  T