YBa2Cu3O7−δ superconducting films with low microwave surface resistance over large areas

Abstract

We demonstrate that in situ off-axis sputtering from a composite target can reproducibly fabricate very high quality YBa2Cu3O7−δ films over large areas of deposition. A significant reduction in the microwave surface resistance, Rs, compared to many previously reported values is found. Rs values at 10 GHz were found to be as low as 20 μΩ at 4.2 K and 450 μΩ at 77 K. A systematic variation of several properties including the transition temperature, critical current density at high magnetic fields, and the c-axis lattice parameter across the 3.8 cm×3.8 cm (14.5 cm2) deposition area was found.