Vortex phases and dynamics in YBa$_{2}$Cu$_{3}$O$_{7}$+BaZrO$_{3}$ films as a function of angle and field up to 50 Tesla

Studying the vortex solid-liquid transition (resistivity=0) in high T$_{c}$ superconductors is scientifically and technologically relevant. We have used low current transport measurements to study the melting line of YBa$_{2}$Cu$_{3}$O$_{7}$ films with and without BaZrO$_{3}$ additions in fields up to 50 T. Samples with mostly extended particle defects, mostly columnar defects, or a mixture of both will be compared. Plain YBa$_{2}$Cu$_{3}$O$_{7}$ shows correlated pinning along the crystalline axes and the emergence of a smectic phase when field is aligned with the a-b plane. Inclusion of BaZrO$_{3}$ not only alters the angular dependence of the irreversibility line indicating the stronger influence of c-axis correlated pinning, but also affects dissipation in the vortex-liquid state over the entire angular range. We will discuss the results in terms of vortex pinning, the corresponding types of phase transitions, micro-structural analysis, and information obtained from critical current measurements.