Flux Pinning of NdBa2Cu3O7-δ Superconducting Films by Laser Ablation Method

Abstract

Thin films of NdBa2Cu307-δ (NdBCO) were fabricated on SrTiO3 substrate by pulsed laser deposition (PLD). In present NdBCO films, a thermally activated flux motion is prominently observed near onset of the resistive transition in the magnetic fields. Transport current measurements by general four probe method yield an irreversibility field B irr of 7T at 77K for the NdBCO film with a critical temperature T c = 89 K, in magnetic fields parallel to the c-axis of the film. At zero-field, the film has a critical current density J c at 77K of about 1 × 106 A/cm2. In the magnetic fields parallel to the c-axis, J c values are 1 × 105 A/cm2 (2T) and 2 × 104 A/cm2 (4T). To enhance J c values in the magnetic fields it is required to increase B irr , which is related to T c values and the effective pinning centers in the films.