Effects of Thin SrO Buffer Layer on Dielectric and Superconducting Properties of YBa2Cu3O7-δ/Sr2AlTaO6/YBa2Cu3O7-δ Multilayers

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YBa2Cu3O7-δ(YBCO)/Sr2AlTaO6(SAT)/YBa2Cu3O7-δ(YBCO) multilayers were fabricated to investigate their applicability to electronic devices such as single flux quantum devices. The effects of a few-nm-thick SrO buffer layer between the 300-nm-thick SAT and the upper YBCO layer on their dielectric and superconducting properties were examined. It was found that insertion of only a 5-nm-thick SrO layer substantially decreased the probability of poor isolation between the upper and lower YBCO layers without degrading the superconducting properties of the upper YBCO layer. On the other hand, slight decreases in $T_{\text{c}}$ and $J_{\text{c}}$ values were observed for the case of thicker SrO layers, which was attributed to degradation of crystallinity in the upper YBCO layer. The results of insulating properties, compositional analyses, and scanning electron microscopy observation strongly suggest that the SrO buffer layer suppresses diffusion of upper YBCO elements into the grain boundaries of the SAT layer.
2003-03-15