Scaling behavior near transition temperature in Al-doped YBa2Cu3O7 superconducting thin films

Magnetization measurements of laser-ablated Al-doped YBa2Cu3O7 superconducting thin films in fields up to 12 T were performed for different dopant concentrations. The critical current density Jc was strongly dependent on both applied magnetic field and Al concentration. However, in all samples with different concentrations, Jc was found to scale very well to a formula Jc=Jc(0)[1−T/Tc]n. In addition, the pinning force ( F ⇀ p= J ⇀ cx H ⇀ ) extracted from magnetization loops scaled well to a relation of the form Fp~hp(1−h)q, where h is the reduced field and p and q are scaling parameters [p∼0.70 and q∼1.70]. This type of scaling can be easily discussed in terms of flux line shear model. The extracted scaling law was not affected greatly by thermal fluctuations or vortex phase transition near Tc, suggesting a small effect of thermal fluctuations on superconducting properties in the vortex state.