Angular dependence of the high-frequency vortex response in YBa2Cu3O7-x thin film with self-assembled BaZrO3 nanorods

We present a microwave study of the angular dependence of the flux-flow resistivity ρff and of the pinning constant kp in YBCO thin films containing BZO nanorods. We find that BZO nanorods are very efficient pinning centers, even in tilted fields. We find that ρff is a scaling function of a reduced field H/f(θ). We extend a model for the anisotropic motion of vortices in uniaxially anisotropic superconductor, able to describe the experimental f(θ) on the basis of only the intrinsic anisotropy of YBCO. The pinning constant kp, by contrast, exhibits different field dependences in different angular ranges, consistent with pinning by BZO at angles as large as 60°, and with pinning along the a,b planes as originating from the same mechanism as in pure YBCO with the field along the c axis.