Transport properties of low angle grain boundaries in Y1−xCaxBa2Cu3O7−δ films at high magnetic fields

Abstract

The critical current density of grain boundaries and grains in Y1−xCaxBa2Cu3O7−δ films has been measured in magnetic fields up to 10T. As a function of temperature the critical current densities across 8° [001]-tilt boundaries display a maximum at ≈15–20K for 0.04⩽x⩽0.2 and fields of several teslas. Opposite to the behavior of large angle grain boundaries, calcium doping is found not to enhance the critical current densities of low angle grain boundaries (θ⩽8°).