earticle

영어

We investigated the flux pinning properties of GdBa2Cu3O7-x (GdBCO) superconducting films grown on a LaFeO3 (LFO) buffer layer forming a bilayer structure. LFO films with different thicknesses and GdBCO thin films were all prepared by using a pulsed laser deposition technique. The magnetization measurements revealed that the critical current density of the GdBCO bilayer structure with the LFO buffer layer increased in low magnetic field regions compared to pure GdBCO films. Notably, the variation in critical current density and the position of the maximum pinning force density did not exhibit a simple dependence on the LFO buffer layer thickness. Dew-Hughes’ model fitting confirmed that normal surface pinning is the primary pinning mechanism for both the thinnest and the thickest LFO films. However, for intermediate LFO buffer layer thickness, additional pinning mechanisms beyond normal surface pinning were identified, likely due to the defects from misoriented crystallites, as indicated by the close correlation between the fitting exponent and the grain size of the bilayer structure.