Vortex pinning by a Gaussian splay of columnar defects in YBa2Cu3O7

A particular configuration of columnar defects (Gaussian splay) has been in stalled in a YBa2Cu3O7 Single crystal by irradiation with heavy ions. The i nfluence of this kind of splay on the pinning efficiency has been very cont roversial in the literature. In the present study, the Gaussian splay has b een achieved by defocusing the incident ion beam through a metallic foil. I ts pinning efficiency has been compared to that of a standard configuration of tracks parallel to the c axis. In the largest part of the H-T plane, it is shown that the persistent current densities are actually higher in the Gaussian splay than in the parallel configuration.