Microwave properties of YBa$_2$Cu$_3$O$_{7-\delta}$ films with BaZrO$_3$   nanoinclusions
  We present measurements of the microwave complex surface impedance at 47.7 GHz in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films deposited by pulsed laser deposition with the explicit goal to introduce BaZrO$_3$ (BZO) nanoinclusions. Composite targets obtained by addition of BZO powder in molar percents ranging from 2.5 to 7 mol.% have been prepared and characterized. Measurements of the microwave surface impedance indicate a broadened transition in zero field, however compensated by a very large pinning frequency, indicating that while intergrain properties are still to be optimized the effect of nanometric inclusions substantially enhances the intragrain vortex pinning. 
N. Pompeo, E. Silva, R. Marcon, V. Galluzzi, G. Celentano, A. Augieri,   T. Petrisor