A new 45° homo-biepitaxial YBCO grain boundary junction process fabricated using off-axis RF sputtering

Abstract

Using the off-axis RF magnetron sputtering method, we successfully fabricated YBCO thin films on YSZ [0 0 1] substrates with two distinct in-plane orientations, namely, YBCO [1 0 0] ‖YSZ [1 0 0] (0° in-plane orientation) at 825 °C and YBCO [1 1 0]‖ YSZ [1 0 0] (45° in-plane orientation) at 670 °C. Both orientations of thin films have critical temperatures TC0 in the range 86–88 K and critical current densities in the range 9 × 106–1.2 × 107 A cm−2 at 5 K. Using a thin YBCO film deposited at 825 °C as the seed layer, we fabricated the 45° grain boundary junction. The critical current densities of our 45° grain boundary junction are in the range 103–104 A cm−2 at 4.2 K and the I–V curves are RSJ-like. They are comparable to those of 45° grain boundary junctions created using the pulse laser deposition technique.