Angle-resolved critical transport-current density ofYBa2Cu3

Epitaxial ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ thin films irradiated with swift heavy ions under different directions showed a strongly changed angular dependence of the critical current density ${\mathit{J}}_{\mathit{c}}$(B,T,\ensuremath{\vartheta}) in the mixed state. Additional peaks, which dominate the angular dependence of ${\mathit{J}}_{\mathit{c}}$, appear at angles where the magnetic field is parallel to the irradiation direction, due to the strong pinning of the introduced linear defects. Irradiated ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$/${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ superlattices, however, reveal no additional ${\mathit{J}}_{\mathit{c}}$ peaks but an isotropic ${\mathit{J}}_{\mathit{c}}$ enhancement in a wide angular range. This contrary behavior could be explained by flux lines of different dimensionality.