Vortex oscillations in TFA-grown YBCO thin-films with BZO nanoparticles

An ac susceptibility methodology has been applied to investigate the vortex dynamics of YBa2Cu3O7−x-BaZrO3 nanocomposites grown by the chemical solution deposition TFA route, close to the irreversibility line. By analysing the linear, non-dissipative Campbell regime at low ac fields, we determined the temperature and field dependence of the restoring pinning constant, αL(Hdc, T), characterising the harmonic oscillation of vortices inside their potential wells. Different than standard TFA-YBCO films, BZO nanocomposites displayed increasing αL(Hdc) curves in the whole studied (Hdc, T) phase diagram, a behavior not predicted by the standard collective theory. We suggest results may be explained by the softening of the vortex-lattice, owed to the microstrain induced by the nanoparticles in the YBCO matrix.