Anisotropic transport properties of in-plane-aligneda-axisYBa2Cu3O7films

We have grown a-axis ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ films aligned in the plane of the substrate (100) ${\mathrm{LaSrGaO}}_{4}$ by off-axis sputtering. X-ray and TEM analysis show a single predominant orientation of the b and c axes in these films. In-plane texture x-ray scans and Rutherford backscattering spectroscopy channeling reveal good crystalline quality. TEM analysis shows antiphase boundaries in the [010] direction and stacking fault boundaries in the [001] direction. We obtain an anisotropy ratio in resistivity of 8. The anisotropy in resistivity as well as in critical current density is less than that in single crystals. The reduction can be accounted for by the small percentage of misoriented grains in these films. We also investigate the resistive properties of antiphase boundaries and stacking fault boundaries. The field dependence of the critical current density in the [010] and [001] directions is similar to that of c-axis films, which is known not to be weak link limited.