A comparison of the influence of CeO_2 and In doped CeO_2 interlayer on the properties of the YGBCO/interlayer/YGBCO tri-layer films deposited by pulsed laser deposition

摘要

High critical current (I-c) has long been proved important to REBa2Cu3O7-delta (REBCO or RE123) superconductor for the practical applications. To achieve high I-c values, the primary way is to increase the thickness of superconducting layer and to enhance high critical current density (J(c)). However, J(c) drops precipitously with increasing the thickness of the films. This phenomenon is called the thickness effect, which can be effectively inhibited by fabricating superconductor/interlayer/superconductor tri-layer structure. In this study, a series of YGBCO/CeO2/YGBCO and YGBCO/In doped CeO2(CeO2 + In)/YGBCO tri-layer films with different interlayer thickness were fabricated. The microstructure, surface morphology and superconducting property of these samples were measured. It was found that all the tri-layer films had pure c-axis orientation. When using CeO2 film as an interlayer, the two YGBCO layers in the tri-layer films were almost completely isolated, resulting in the low I(c)values, which were equivalent to the I-c of a single YGBCO layer. While using CeO2 + In film as an interlayer, the I-c values of all the YGBCO/CeO2+ In/YGBCO trilayers were almost double the I(c)of a single YGBCO layer, and the I-c values of the trilayers firstly slow increased and then decreased with increasing the thickness of CeO2 + In interlayer. Under the optimal experimental parameters, the I-c value was much higher than that of the a double YGBCO layer without interlayer. The thickness effect of superconducting layer can be effectively inhibited by inserting CeO2+ In interlayer with wide thickness range.