CRITICAL-CURRENT DENSITY AND FLUX-PINNING IN Y1-XHOXBA2CU3O7-DELTA EPITAXIAL-FILMS

The critical current density J(c) of Y1-xHoxBa2Cu3O7-delta (YHBCO) epi taxial thin films with x=0, 0.2, 0.4, 0.7 at various temperatures and magnetic fields has been measured magnetically. The J(c) and flux pinn ing density Fp values are significantly enhanced with the Ho substitut e amount x with the optimal effect achieved at Ho concentration around x = 0.4 in the entire measured temperature (30-77 K) and magnetic fie ld (0-3 T) ranges. X-ray diffraction patterns have shown that the grea ter the lattice deformation, the higher the J(c) of the films.