Measurement of Vortex Parameters and Pinning in YBa2Cu3O7−x with BaZrO3 Nanoinclusions.

We investigate the pinning strength in YBa2 Cu3 O7−x films with BaZrO3 nanoinclusions. We use microwave (47 GHz) currents to induce vortex shaking and we measure the magnetic field dependent complex surface impedance. To clarify the role of different engineered pinning centers on the vortex dynamics, we investigated different YBa2 Cu3 O7−x /BaZrO3 films: 1) films grown by Pulsed Laser Deposition on single crystal substrates, where the inclusions give rise to elongated nanorods; 2) films grown by metallorganic deposition, where the inclusions give rise to nanospheroids; and finally 3) films grown on metallic buffered substrates, of great importance for the development of coated conductors. Using a dielectric resonator technique, we obtained data for the complex resistivity as a function of moderate dc fields up to μ0H = 0.8 T. We focused the analysis on the vortex pinning parameter r(H). In laser-ablated samples on single-crystal substrates we observe a change of pinning regime with the introduction of BZO, consistent with previous Jc and microwave measurements. However, in films grown on metallic buffered substrates and in chemically deposited films such a change is absent.