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

An ac susceptibility methodology has been applied to investigate the vortex dynamics of YBa₂Cu₃O_7−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, α_L(H_dc, T), characterising the harmonic oscillation of vortices inside their potential wells. Different than standard TFA–YBCO films, BZO nanocomposites displayed increasing α_L(H_dc) curves in the whole studied (H_dc, 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.