High quality a-axis outgrowth on c-axis Y_1-xCa _xBa₂Cu₃O_7-δ

The large amplitude of the high T_c (HTSC) superconducting gap is attractive for improved electronic applications. However, the study of such HTSC cuprates has uncovered that unlike the s-wave order parameter of the low T_c superconductors (LTSC), an angle dependent d_x2-y2 wavefunction is the dominant order parameter in such compounds. This symmetry causes low energy surface bound states, detrimental for applications, except at (100) oriented surfaces. It is therefore essential to have a smooth and well oriented surface of the crystallographic a-axis (100). In this work we present a study of an unconventional way to attain such surfaces in the form of a-axis outgrowth on a c-axis surface of sputtered Y_1-xCa_xBa ₂Cu₃O_7-δ thin film. The grain topography was tested using x-ray, SEM and AFM together with point contact and tunnel junctions measurements.