The critical current, Jc, of highly twinned films was measured as a function of temperature, magnetic field and angle. Over much of the parameter space, strong suppression of Jc for fields in the directions was observed. This was quantitatively modeled as a flux-cutting mediated vortex channeling. For certain temperatures and fields, a cross-over occurred to a regime in which channeling was blocked and the twin boundaries acted as planar pinning centers so that twin boundary pinning enhanced the overall Jc. In this regime, intrinsic pinning along the twin boundaries was comparable to that between the twins.

Crossover between Channeling and Pinning at Twin Boundaries in YBa2Cu3O7 Thin Films. A.Palau, J.H.Durrell, J.L.MacManus-Driscoll, S.Harrington, T.Puig, F.Sandiumenge, X.Obradors, M.G.Blamire: Physical Review Letters, 2006, 97[25], 257002 (3pp)