论文标题
对超导体/正常金属超级晶格的穿透深度和相干长度的扭曲
Distortions to the penetration depth and coherence length of superconductor/normal-metal superlattices
论文作者
论文摘要
与可比厚度的NB薄膜相比，鉴于其有利的表面粗糙度，由NB和普通金属垫片（$ n $）组成的超导（$ s $）薄膜超级晶体超级晶胶已在约瑟夫森交界处广泛使用。在这项工作中，我们表征了伦敦穿透深度和Ginzburg-Landau连贯性长度的$ s/n $超晶格，使用偏振中子反射仪和电气传输。尽管普通的金属垫片仅占超级晶格厚度的大约8％，但我们出人意料地发现，与单个可比厚度的单个NB膜相比，$ s $层之间的这些薄$ n $垫片在$ s $层之间引起了巨大的增长。使用有效的平面内和面外相干长度的测量值，我们量化了超晶格样品的诱导各向异性，并将其与单个NB膜样品进行比较。从这些结果中，我们发现超晶格的行为与分层的2D超导体相似。
Superconducting ($S$) thin film superlattices composed of Nb and a normal metal spacer ($N$) have been extensively utilized in Josephson junctions given their favorable surface roughness compared to Nb films of comparable thickness. In this work, we characterize the London penetration depth and Ginzburg-Landau coherence lengths of $S/N$ superlattices using polarized neutron reflectometry and electrical transport. Despite the normal metal spacer layers being only approximately 8% of the total superlattice thickness, we surprisingly find that the introduction of these thin $N$ spacers between $S$ layers leads to a dramatic increase in the measured London penetration depth compared to that of a single Nb film of comparable thickness. Using the measured values for the effective in- and out-of-plane coherence lengths, we quantify the induced anisotropy of the superlattice samples and compare to a single Nb film sample. From these results, we find that that the superlattices behave similarly to layered 2D superconductors.
