Abstract

We studied homogeneity in the microwave surface resistance of Au-coated YBa₂Cu₃O_7−δ (Au/YBCO) films. The Au/YBCO film with 4-inches in diameter was prepared in-situ with the thicknesses of 68 nm and 365 nm for the Au layer and the YBa₂Cu₃O_7−δ (YBCO) layer, respectively. We measured the effective surface resistance (R_S,eff) of the Au/YBCO film at temperatures of 25 K, 60 K, 70 K, and 77 K, respectively, at 29 different positions on the film. The R_S,eff values were analyzed with the finite thicknesses of the Au and the YBCO layers taken into consideration. The local R_S,eff values of the Au/YBCO film appeared to be almost uniform at 25 K. Meanwhile significant positional dependences were observed for the R_S,eff of the Au/YBCO film at 60 K, 70 K and 77 K, respectively, which seemed to be due to non-uniform local penetration depth (λ) of the YBCO layer rather than due to variations in the local real-part conductivity of the YBCO layer. The observed results could not be attributed to the properties of the Au layer. At temperatures below the critical temperature of YBCO, the observed R_S,eff values of the Au/YBCO film were significantly lower than those estimated using the surface resistance of Au and YBCO, which reflected proximity effects of the normal-metal Au layer in contact with the superconducting YBCO layer. Homogeneity in the R_S,eff of the Au/YBCO film might be correlated with the distributions in the local λ of the YBCO layer, providing valuable information needed for designing microwave filters.

Graphic Abstract

中文翻译：

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涂金的大型YBa 2 Cu 3 O7-δ超导薄膜的微波表面电阻均质性

摘要

我们在金涂覆的YBa的微波表面电阻均匀性研究₂的Cu ₃ ö _7-δ（AU / YBCO）膜。用直径为4英寸的金/ YBCO薄膜在原位制备的68 nm和Au层和所述的YBa 365nm的厚度₂的Cu ₃ ö _7-δ（YBCO）层，分别。我们分别在25 K，60 K，70 K和77 K的温度下在膜上的29个不同位置测量了Au / YBCO膜的有效表面电阻（R _S，eff）。的[R _S，EFF值与Au构成的有限厚度和考虑到YBCO层进行分析。本地R _S，effAu / YBCO薄膜在25 K时的值似乎几乎是均匀的。与此同时_， Au / YBCO薄膜在60 K，70 K和77 K时的R _S，eff的显着位置相关性也很明显。这是由于YBCO层的局部穿透深度（λ）不均匀，而不是由于YBCO层的局部实部电导率变化所致。观察到的结果不能归因于Au层的性质。在低于YBCO临界温度的温度下，观察到的R _S，effAu / YBCO膜的阻值明显低于使用Au和YBCO的表面电阻估计的值，这反映了普通金属Au层与超导YBCO层接触的邻近效应。Au / YBCO膜的Rs _，eff的均质性可能与YBCO层的局部λ中的分布相关，为设计微波滤波器提供了有价值的信息。

图形摘要