Magnetotransport and flux pinning characteristics in RBa2Cu3O7−δ (R=Gd,Eu,Nd) and (Gd1/3Eu1/3Nd1/3)Ba2Cu3O7−δ high-Tc superconducting thin films on SrTiO3(100)

Abstract

High-quality mono rare earth RBa2Cu3O7−δ (R=Gd,Eu,Nd) and mixed rare earth (Gd1/3Eu1/3Nd1/3)Ba2Cu3O7−δ (GEN123) films were prepared by off-axis laser deposition, and their transport and flux pinning characteristics were experimentally studied. Enhanced flux pinning due to rare earth mixing is evidenced by high transport critical current density (Jc) and an upward shifted irreversibility line defined by zero-resistance criterion. In contrast, the characteristic field, i.e. the accommodation field (Hacc), identified from the field dependence of transport Jc, shows no increase due to rare earth mixing. It is found that Hacc vs T can be scaled by a negative exponential relation at a wide range of temperatures, and the field anisotropy of Hacc appears pronounced as the field direction varies from H∥c to H∥(a,b). According to the analysis on the temperature dependence of Jc, it is suggested that the flux pinning mechanism in mixed rare earth samples is dominated by stress-field centers which may be induced by dislocations and enhanced by lattice mismatch in GEN123 films. Finally, the fluctuation of vortex phases is discussed with respect to correlated and uncorrelated structure disorders in epitaxial 123 thin films.

Source-reported materials — not catalogue approval

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