Intrinsic pinning and lock-in transition of flux lines in layered type-II superconductors

Reversible flux penetration in uniaxial layered superconductors is studied, taking into account the possible trapping of vortex cores between layers. This is found to induce high intrinsic critical currents parallel to the layers. In low and intermediate fields, the flux lines experience a lock-in transition towards the layer plane, as a function of the field direction or intensity. Application to anisotropic high-Tc materials is discussed.