Enhanced vortex pinning in melt-textured YBCO by means of gold-ion-induced defects.

We have studied the effects of 235 MeVAu ion implantation on critical current density, creep rate and irreversibility line of YBCO melt-textured bulk samples. The fluence was 1.25·10 ions/cm, corresponding to a dose equivalent field of 2.5 T. We created two surface layers with correlated defects on the opposite sides of the sample, in such a way that the irradiated part was about 13% of the total volume. Such a surface irradiation caused a quite large widening of the irreversibility region in the B-T phase diagram. Critical current enhancements -having different behaviours as a function of field in different temperature ranges and reaching more pronounced values at higher temperatures and fields-were found. [ABSTRACT FROM AUTHOR]