Enhanced flux pinning in YBa2Cu3O7−δthin films using Nb-based double perovskite additions

The addition of a new niobate double perovskite pinning phase to YBa 2 Cu 3 O 7−δ thin films grown by pulsed laser deposition is reported. The YBa 2 NbO 6 phase self-assembles into stacks of ∼10 nm second phase particles, aligned with the c -axis of the YBa 2 Cu 3 O 7−δ . The YBa 2 Cu 3 O 7−δ / YBa 2 NbO 6 composite thin films have enhanced critical current, by a factor of 2, at 1 T ( ) over the pure YBa 2 Cu 3 O 7−δ , whilst maintaining a high transition temperature. Niobium does not substitute in the YBa 2 Cu 3 O 7−δ matrix. This, together with the high stability of the second phase formed, makes it an ideal pinning additive.